OBD-II Code P1340: Cam/Crank Sensor Correlation or Circuit Fault

What Does P1340 Mean?

P1340 is a manufacturer-specific code signaling a problem with the engine's timing or ignition system. The engine control unit (ECU) detects a disagreement between the crankshaft and camshaft position sensors, or a fault in a specific sensor's circuit. The ECU cannot determine the precise position of the engine's rotating parts. Definitions vary by manufacturer: timing correlation (VW, Audi), sensor circuit fault (Ford, Toyota), or misfire detection (BMW, Peugeot).

Technical definition: The official SAE/OBD-II definition for P1340 varies by manufacturer. For Volkswagen and Audi, it is "Crankshaft Position/Camshaft Position Sensor Signals Out of Sequence". For Ford, it is "Camshaft Position Sensor 'B' Circuit Malfunction". For Toyota, it means "Camshaft Position Sensor 'A' (Bank 1 Sensor 2) Circuit Malfunction". For BMW, it uniquely means "Multiple Cylinder Misfire During Start". In all cases, it points to a failure in the system tracking mechanical or electrical state for proper timing and combustion.

Can I Drive With P1340?

No — Do Not Drive. Do not drive. You will likely experience stalling, poor acceleration, and bad fuel economy. A persistent misfire destroys the catalytic converter, a repair costing $800-$2,500. If the cause is a failing timing chain, continued driving causes the chain to break, resulting in catastrophic engine failure with repair costs exceeding the vehicle's value.

Common Causes

• Faulty Camshaft Position Sensor (Very Common) — The sensor fails internally due to heat and age, sending an incorrect or dead signal to the computer. This is the most frequent cause of the code.
• Faulty Crankshaft Position Sensor (Common) — The crankshaft sensor fails similarly to the camshaft sensor, leading to a correlation error even if the camshaft sensor works perfectly.
• Damaged Wiring or Connectors (Common) — The wiring harness to the camshaft or crankshaft sensor frays, corrodes, or disconnects, interrupting the signal. This frequently happens to wires routed near hot or moving parts, like a serpentine belt.
• Stretched Timing Chain or Failed Tensioner (Less Common) — Over time, a timing chain stretches, a belt jumps a tooth, or a hydraulic tensioner fails. This alters the actual mechanical timing between the crank and cam, which the sensors correctly report as a correlation fault.
• Use of Low-Quality Aftermarket Sensors (Less Common) — Low-cost, non-OEM camshaft or crankshaft sensors are frequently faulty out of the box or fail quickly, causing the P1340 code to persist or return shortly after repair. OEM or high-quality aftermarket parts are mandatory.
• Incorrectly Installed Timing Components (Less Common) — If the code appears shortly after a timing belt or chain service, the components were installed incorrectly, with the timing marks misaligned by one or more teeth.
• Corrosion in ECU or Main Wiring Harness Connectors (Rare) — Particularly on Ford Falcons and in humid climates, moisture intrusion and corrosion at the main Engine Control Unit (ECU/PCM) connector causes a poor connection and triggers this code, even when the sensors are fine.
• Low Engine Oil or Poor Oil Quality (Rare) — On engines with oil-pressure-driven variable valve timing (VVT) systems, low or dirty oil prevents the camshaft phasers from adjusting correctly, causing a timing correlation issue.
• Damaged or Contaminated Reluctor Wheel (Rare) — The sensors read a toothed reluctor ring. If this wheel has bent teeth, or if metal shavings stick to the magnetic sensor tip, it disrupts the signal and causes a P1340 code.
• Oil Contamination of Spark Plug Wells (Rare) — On certain engines, like the Peugeot 1.6 THP, a leaking valve cover gasket allows oil to pool in the spark plug wells. This fouls the ignition coil and spark plug, causing a misfire the ECU interprets as a P1340 fault.
• Faulty Engine Control Unit (ECU) (Very Rare) — The engine's computer fails to correctly interpret the signals from the sensors. Consider this only after exhausting all other possibilities.

Symptoms

• Engine is Hard to Start or Won't Start — The ECU requires correct timing signals to start the engine; without them, it cranks excessively before firing up, or fails to start entirely.
• Rough Idle and Stalling — The engine runs unevenly, shakes at a stop, or shuts off unexpectedly while driving or idling.
• Reduced Engine Power and Poor Acceleration — The car feels sluggish and struggles to reach highway speeds because fuel and ignition timing are compromised.
• Decreased Fuel Economy — Incorrect engine timing forces the engine to burn fuel inefficiently, noticeably dropping your MPG.
• Audible Noise from Timing Chain — A stretched chain or failed tensioner produces a distinct rattling or whirring noise from the engine block.
• Burning Oil or Fuel Smell — A misfire forces unburnt fuel into the exhaust, creating a strong fuel smell. If an oil leak is the root cause, you will smell burning oil.
• Check Engine Light is On (also visible on scanner) — This is the most common and often the first sign of a problem.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this code.

Common Fixes & Costs

• Replacing the Camshaft Position Sensor — Parts: $60-$150, Labor: $100-$200, ~1.1 hr book time (DIY)
  VW Jetta/Golf (VR6/2.5L): OEM
  Audi A4 (1.8T): OEM
  BMW 3-Series (E46 M54): OEM
• Replacing the Crankshaft Position Sensor — Parts: $50-$120, Labor: $150-$300, ~2 hr book time (Intermediate)
• Repairing Damaged Wiring or Connectors — Parts: $10-$60, Labor: $120-$250, ~1.5 hr book time (Intermediate)
• Replacing the Timing Chain, Guides, and Tensioners — Parts: $400-$900, Labor: $1000-$2000, ~8 hr book time (Professional)
  VW Jetta/Golf (VR6): OEM
  Audi A4 (1.8T): OEM
• Replacing the Timing Belt and Tensioner — Parts: $150-$400, Labor: $500-$1100, ~4.5 hr book time (Professional)

DIY vs Professional

• Replacing the Camshaft Position Sensor — Beginner:
  Tools: Basic hand tools (socket set, screwdrivers).
• Repairing Damaged Wiring or Connectors — Beginner:
  Tools: Multimeter, wire strippers, wire cutters, heat shrink tubing, soldering iron (recommended), or quality butt connectors.
• Replacing the Timing Belt/Chain — Beginner:
  Tools: Extensive socket/wrench set, engine-specific timing locking tools, torque wrench, floor jack, jack stands, service manual.

Used vs. New Parts: Buying Guide

When a used part is worth it: Buying used electronic parts like a camshaft position sensor is not recommended due to the low cost of new parts and the high risk of the used part failing. A used sensor only makes sense as a temporary, emergency part to get a vehicle running.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

Donor quality checklist:

• Verify the part number is an exact match for your vehicle.
• Avoid sensors from high-mileage vehicles or those that sat in a junkyard exposed to weather.
• Prefer parts from vehicles scrapped due to accidents rather than engine failure.

Decision logic:

• If The new OEM or high-quality aftermarket sensor costs less than $150. → Always buy new. The reliability and warranty are worth the cost.
• If The vehicle is very old and has low value, and the budget is extremely tight. → A used part from a low-mileage donor is a gamble but may be acceptable. Expect a much shorter lifespan.
• If The part has a known high failure rate (e.g., certain aftermarket brands). → Strongly favor a new OEM part to avoid repeat failures.

Warranty tradeoff: Used parts typically have a 30-90 day warranty covering only the part itself. New aftermarket parts offer a 1-year to limited lifetime warranty. New OEM parts offer a 1-2 year warranty.

Worst-case if a used part fails: $200-$400 if a used sensor fails after installation, requiring repeat labor costs plus the price of another sensor.

What Happens If You Wait — Timeline

1. 0-1 month: Code is set, MIL on. May be intermittent. Symptoms are minor or non-existent, possibly a slightly longer crank time or a brief stumble at idle. (MPG impact: 0-5%% · Added cost: $0-40 in wasted fuel.)
2. 1-3 months: Symptoms become more consistent. Rough idle, hesitation on acceleration, and noticeable stalling become more frequent. The risk of stalling in traffic increases. (MPG impact: 5-15%% · Added cost: $50-150 in wasted fuel.)
3. 3-6 months: If the cause is timing-related, persistent misfires begin to damage other components. Unburnt fuel starts to overheat the catalytic converter, reducing its efficiency and beginning to melt the internal substrate. (MPG impact: 15-25%% · Added cost: $1200-$2800 for the now-necessary catalytic converter replacement, in addition to the original repair.)
4. 6+ months: Worst-case scenario for a mechanical timing fault. The stretched timing chain jumps several teeth or breaks entirely. In an interference engine, this causes immediate, catastrophic piston-to-valve collision. (MPG impact: 100% (engine non-operational)% · Added cost: $3000-$8000+ for a complete engine rebuild or replacement, a cost that often exceeds the vehicle's total value.)

Cost of Not Fixing It

• 0-1 month: Noticeable drop in fuel economy (5-15%), rough idle, and potential stalling. Risk of being stranded. (Added cost: Negligible, besides extra fuel costs.)
• 1-6 months: Persistent misfires cause unburnt fuel to enter the exhaust, overheating and melting the internal structure of the catalytic converter. (Added cost: $1200-$2800 for catalytic converter replacement.)
• 6+ months: If the cause is a mechanical timing issue, continued operation causes the chain to break or jump teeth. This causes catastrophic engine damage as pistons and valves collide. (Added cost: $3000-$8000+ for major engine repair or replacement, often exceeding the vehicle's value.)

Diagnosis Steps

1. Read Codes, Freeze Frame Data & Research Definition
   Use an OBD-II scanner to confirm P1340 and any other codes. Research the exact definition for your vehicle's make and model. Note the freeze frame data, which shows the engine's state when the fault occurred. Check for related codes like P0340, P0335, or P0016.
   Tools: OBD-II Scanner, Access to Service Manual/Online Resources (Beginner)
2. Analyze Live Data for Cam/Crank Correlation (Pro Tip)
   Using an advanced scan tool, access the live data PIDs for camshaft and crankshaft position. On VW/Audi vehicles, check Measuring Value Block 093. The value must be 0° +/- 5°. A value outside this range definitively proves a mechanical timing issue (stretched chain, slipped belt) rather than a sensor failure.
   Tools: Advanced OBD-II Scan Tool (e.g., VCDS, Techstream) (Intermediate)
3. Check Engine Oil Level and Condition
   Verify the engine oil level is correct and the oil is clean. Low or dirty oil causes variable valve timing (VVT) systems to fail, triggering this code instantly on VW/Audi engines.
   Tools: Dipstick, Clean Rag (Beginner)
4. Perform a Thorough Visual Inspection
   Visually inspect the wiring harnesses and connectors for both camshaft and crankshaft sensors. Look for damage, corrosion, melting, or loose connections. On Ford Falcons, check the main ECU/PCM connectors for corrosion. On Toyota V8s, check if the sensor wiring rubbed against the serpentine belt.
   Tools: Flashlight (Beginner)
5. Test Sensor Circuits with a Multimeter
   Check for correct reference voltage (typically 4.5V-5.0V) and a good ground (< 1.5 ohms of resistance to chassis ground) at the sensor connector with the key on. This verifies circuit integrity from the ECU.
   Tools: Multimeter, Vehicle-Specific Service Manual (Intermediate)
6. Test 3-Wire (Hall-Effect) Sensor Signal
   Back-probe the signal wire at the connector. Set your multimeter to DC Volts. While cranking the engine, the voltage must rapidly switch between a low value (near 0V) and a high value (typically 5V). A constant voltage or no voltage proves the sensor failed.
   Tools: Multimeter (with back-probe adapters), Service Manual (Advanced)
7. Test 2-Wire (Inductive) Sensor Resistance and Output
   Disconnect the sensor and measure resistance between the two pins. The value must match manufacturer specifications (typically 200-2,500 Ohms). Infinite or zero resistance indicates a failed sensor. Switch to AC Volts; while cranking, the sensor must produce a small AC voltage (>200mV).
   Tools: Multimeter, Service Manual (Advanced)
8. Analyze Sensor Signals with an Oscilloscope
   This definitively tests the sensors. Verify the sensors produce a clean, square wave (Hall effect) or AC sine wave (magnetic) with no dropouts. Compare the cam and crank patterns to a known-good waveform from a service manual. A good signal that is misaligned proves a mechanical timing problem.
   Tools: Oscilloscope, Vehicle-Specific Service Manual (Advanced)
9. Test Wiring Integrity at the ECU
   If sensor tests are inconclusive, disconnect the battery and the ECU connector. Perform a continuity test on the signal, reference, and ground wires from the sensor connector directly to the corresponding pins at the ECU. This uncovers hidden breaks or high resistance in the harness.
   Tools: Multimeter, ECU Pinout Diagram (Advanced)
10. Inspect Mechanical Timing
    Access the timing components to visually inspect the timing belt or chain for slack, damage, or misalignment of the timing marks on the sprockets, pulleys, and engine block. This is the final step to confirm a mechanical fault.
    Tools: Socket Set, Wrenches, Timing Locking Tools, Vehicle-Specific Service Manual (Advanced)

When This Code Triggers (Freeze-Frame Conditions)

• Engine Coolant Temp: 175-210°F (80-99°C) (Engine is fully warmed up.)
• RPM: 600-2500 RPM (During crank, at idle, or during steady cruise.)
• Engine Load: 20-60% (During light to moderate acceleration or steady highway driving.)
• Vehicle Speed: 0 mph (crank/idle) or 45-65 mph (Fault is detected at startup or during highway driving.)

Related Codes

• P0340 — Generic for Camshaft Position Sensor 'A' Circuit Malfunction. P1340 is manufacturer-specific. If you have both, P1340 provides the more specific diagnostic path.
• P0335 — Generic for Crankshaft Position Sensor 'A' Circuit Malfunction. A P1340 correlation code is triggered by a P0335 fault. P0335 shows a bad signal from the crank sensor, while a P1340 correlation fault shows two good-but-misaligned signals.
• P0016 — Specifically means Crankshaft/Camshaft Position Correlation. This is essentially the generic version of the VW/Audi P1340 definition. They are diagnosed the same way but apply to different manufacturer software.
• P0300 — Means Random/Multiple Cylinder Misfire. Incorrect timing from a P1340 fault is a very common cause of engine misfires. On a BMW, P1340 is a specific type of misfire code itself.

Climate & Environmental Factors

• High Humidity / Coastal Climates: Increases the likelihood of moisture intrusion into electrical connectors, especially main ECU or wiring harness plugs. This leads to corrosion and poor pin contact, triggering a P1340 code even if the sensor is good.
• Extreme Cold Weather: On BMW models where P1340 means 'Misfire During Start', a weak battery struggling in cold weather causes slow engine cranking speed. This prevents the ECU from getting a clear signal from the cam/crank sensors in time, directly causing the code.
• High Heat: Prolonged exposure to high engine bay temperatures accelerates the aging process of plastic sensor housings and internal electronic components, leading to premature failure.

How to Talk to a Mechanic About This Code

Say this: "I have a P1340 code and I'd like to schedule a diagnostic. I understand this code has multiple causes, from a sensor to a timing chain. Please start with a full diagnostic to pinpoint the failure before replacing any parts."

This signals you understand the code's complexity and want a proper diagnosis, not just throwing parts at the problem. It frames the conversation around finding the root cause, preventing unnecessary, expensive repairs.

Avoid saying:

• 'My check engine light is on, can you look at it?' (Too vague, invites a broad, expensive inspection).
• 'Just replace the camshaft sensor.' (Assumes a diagnosis and prevents the shop from finding the true cause, like a wiring issue or timing problem).
• 'Just fix whatever's wrong.' (Gives the shop a blank check to perform repairs without explicit approval).

Questions to ask before authorizing the repair:

• What specific tests did you perform to conclude this is the problem?
• If it is a timing issue, can you show me the data (e.g., VW Measuring Block 093) or scope pattern that confirms it?
• Will you provide a written estimate with a clear breakdown of parts and labor costs?
• What is the warranty on the parts and the labor for this specific repair?

Where to Take It: Dealer vs Independent vs Chain

• Dealer:
  Best for: Vehicles under warranty., Complex manufacturer-specific quirks, especially on German brands like VW, Audi, or BMW where special tools and software are required., Recall-related repairs (e.g., Nissan/Infiniti sensor campaigns).
  Downsides: Highest labor rates, often 1.5x to 2x an independent shop., May recommend more expensive, wholesale repairs instead of targeted fixes. (Typical cost: +50% vs. baseline)
• Independent Shop: Excellent fit. For a VW/Audi, a VAG-specialist indie is the best balance of expertise and cost. For a simple sensor fault on a domestic or Japanese car, most competent indies are well-equipped.
  Best for: Out-of-warranty vehicles where cost is a major factor., Shops specializing in your car's brand (e.g., a 'Euro specialist' for a VW or Audi) offer dealer-level expertise at a lower cost., Building a long-term relationship with a trusted technician.
  Downsides: Quality and expertise vary widely; thorough vetting through reviews and checking for ASE certifications is crucial., May lack the latest manufacturer-specific diagnostic tools. (Typical cost: +0% vs. baseline)
• Chain Shop: Use with caution. Acceptable for a straightforward camshaft sensor replacement if the diagnosis is 100% certain. AVOID for initial diagnosis or any repair involving mechanical timing.
  Best for: Simple, clear-cut repairs where the diagnosis is already certain (e.g., you diagnosed a bad, easily accessible sensor yourself).
  Downsides: Technician skill varies dramatically., High pressure to upsell common services; frequently misdiagnoses a complex P1340 as something simpler., Generally not equipped for in-depth mechanical work like a timing chain replacement. (Typical cost: -10% vs. baseline)

When to Walk Away From the Repair

If the estimated repair cost exceeds 50% of the car's private-party market value, seriously consider selling or trading in the vehicle.

• Car worth $4000, fix is $2500: Walk away. The repair cost is over 60% of the car's value. This is a poor investment.
• Car worth $12000, fix is $2500: Fix it. The repair cost is only about 20% of the car's value and restores its function and reliability.
• Car worth $3000, fix is $350: Fix it. A low-cost sensor replacement is well worth it to keep the car running and maintain its value.

What Scan Tool You Need for This Code

Minimum: A scanner that reads manufacturer-specific codes and views live data streams for the Camshaft and Crankshaft sensors.

A basic $20 reader only shows the P1340 code but lacks the live data needed to see if a sensor is failing or if the timing is out of sync. Live data is essential for this diagnosis.

Budget: BlueDriver Pro (~$100) — Connects to your smartphone via Bluetooth. It reads manufacturer-specific definitions for P1340, views freeze-frame data, and graphs live data from the cam/crank sensors.

Mid-range: Foxwell NT510 Elite (with brand-specific software) (~$180) — Offers deep, dealer-level diagnostics for a specific car make. For a VW/Audi, it accesses Measuring Value Blocks (like Block 093) to definitively check mechanical timing.

Professional: Autel MaxiCOM MK808Z (~$500) — A professional-grade tablet scanner providing full bidirectional control, all-system scanning, and advanced service functions. It graphs cam/crank data and accesses manufacturer-specific PIDs on almost any make.

Rent vs buy: AutoZone and O'Reilly offer loaner tool programs for a fully refunded deposit. However, these are often basic readers. If your P1340 requires checking mechanical timing, you must buy a capable scanner like the Foxwell or Autel.

How to Clear the Code After You Fix It

1. Reconnect battery if disconnected for repair.
2. Use an OBD-II scan tool to clear any stored fault codes.
3. Perform a complete OBD-II drive cycle to allow readiness monitors to run.

Drive cycle (~30 minutes): 1) Cold start (engine temp below 122°F). 2) Idle for 2-3 minutes with electrical loads on. 3) Accelerate to 55 mph and hold steady speed for 3-5 minutes. 4) Coast down to 20 mph without braking. 5) Drive 15-20 minutes in stop-and-go city traffic.

Readiness monitors affected: Catalyst Monitor, EVAP System Monitor, Oxygen (O2) Sensor Monitor, Misfire Monitor

Before emissions retest: drive at least 100 miles to fully set monitors.

Watch out for:

• Clearing the code turns the light off, but it does not set the readiness monitors required to pass an emissions test.
• The code returns immediately if the root cause of the fault has not been correctly repaired.
• Specific monitors like the EVAP system have strict temperature and fuel level conditions that must be met to run their tests.

Will This Fail Emissions / State Inspection?

Yes — this code typically fails an OBD-II emissions inspection.

• California: An illuminated Check Engine Light from code P1340 is an automatic failure. All required OBD readiness monitors must be set to 'Ready'. After repair, a full drive cycle is needed before re-testing.
• New York: The NYS DMV inspection includes an OBD-II scan. An active P1340 code causes the vehicle to fail the emissions portion of the inspection.
• Texas: In counties requiring emissions testing, an illuminated Check Engine Light results in an automatic failure. After repair, drive 50-100 miles to reset the readiness monitors before a re-test.

Most Commonly Affected Vehicles

• Volkswagen Jetta, Golf, Passat (VR6, 2.5L, V6) (1999-2012) — Often caused by stretched timing chains or failed plastic tensioner guides. On V6 engines, slipped press-fit cam sprockets after previous engine work cause this.
• Audi A4, A6, TT (1.8T, 3.0L V6) (1998-2008) — Frequently related to timing chain tensioner failure or incorrect cam/crank correlation. On the 1.8T, low oil pressure from a clogged oil pump pickup causes this.
• BMW 3-Series (E46), 5-Series (E39), X3, Z4 (M54 Engine) (2000-2006) — Unique Definition: 'Multiple Cylinder Misfire During Start'. Causes include a weak battery causing slow cranking, faulty VANOS system, failing ignition coils, or low fuel pressure at startup.
• Nissan Altima, Maxima, Sentra, Pathfinder (1995-2010) — Commonly triggered by failing camshaft or crankshaft position sensors. OEM sensors are strongly recommended. A major recall covered this issue.
• Infiniti G35, I30, QX4 (1996-2012) — Similar to Nissan, sensor failures are a primary cause for this code and were included in a recall campaign.
• Ford (Australia) Falcon (BA, BF) (2002-2010) — On Barra engines, this code is often part of a set with other VCT codes. The cause is frequently traced to moisture and corrosion in the main ECU wiring harness connector. Cleaning the connectors resolves the fault.
• Toyota Tundra, Sequoia, Land Cruiser (2UZ-FE V8) (2000-2009) — Often points to a faulty camshaft position sensor or a damaged wiring harness. The sensor wiring is commonly mis-routed and gets damaged by the serpentine belt.
• Peugeot 207, 308, RCZ (1.6 THP Engine) (2007-2015) — The definition is often 'Cylinder 4 Misfire'. This is commonly caused by a failed ignition coil, exacerbated by oil leaking from the valve cover gasket into the spark plug well.
• Ferrari 360 Modena (1999-2005) — Code definition is 'Alignment between camshaft and crankshaft signal (Bank 2)'. It almost always appears after an incorrect timing belt service where the cams were not locked properly.

Manufacturer-Specific Notes

• Volkswagen/Audi: On VR6 and V6 engines, this code is frequently caused by stretched timing chains. Diagnosis is confirmed by checking Measuring Value Block 093 with a compatible scan tool; the value must be 0° +/- 5°. A value outside this range indicates a mechanical timing issue.
• Nissan/Infiniti: A voluntary recall campaign (NHTSA ID: 03V-455) was issued for faulty camshaft and crankshaft position sensors on many 2000-2003 models. The service procedure often required replacing cam and crank sensors as a set.
• BMW: P1340 means 'Multiple Cylinder Misfire During Start'. It is not a sensor correlation code. Diagnosis focuses on startup conditions: battery voltage/cranking speed, fuel pressure, and ignition components. A weak battery is a common cause.
• Toyota: On 2UZ-FE V8 engines, the wiring for the camshaft position sensor is notorious for being damaged by the serpentine belt after a previous repair, causing an intermittent short and triggering the code.
• Ford: The definition is typically 'Camshaft Position Sensor 'B' Circuit Malfunction', pointing specifically to the sensor for the second camshaft on a DOHC engine or the sensor on Bank 2.
• Peugeot: For the 1.6 THP engine, P1340 often indicates a misfire on cylinder 4. The primary suspect is a failed ignition coil, frequently caused by a leaking valve cover gasket that allows oil to foul the coil.
• Ferrari: On the 360 Modena, this code almost exclusively points to a mechanical timing error on Bank 2, usually caused by performing a timing belt change without using the proper camshaft locking tools.

Real Owner Stories

2003 VW Jetta VR6 with 121k miles, audible rattle

Check Engine Light came on with code P1340. The engine had a noticeable rattling noise. A mechanic suggested replacing the cam/crank sensors, while another suggested timing chains.

Outcome: The consensus from experienced mechanics was that timing chain and guide replacement is necessary. The estimated cost was high ($3,000-$4,000) due to the labor-intensive nature of the job (transmission removal required).

Lesson: On a VW VR6, an audible rattle combined with P1340 is a near-certain indicator of a mechanical timing problem (stretched chains/failed guides), not a simple sensor issue. Do not waste money on sensors before confirming the mechanical timing.

2006 BMW E46 3-series, multiple codes after sitting

Car started with a very rough idle, backfiring, and threw multiple codes including P1340 (Misfire During Start) and others for MAF sensor and multiple cylinder misfires after the battery died and was recharged.

Outcome: Multiple forum members confirmed that a weak or dying battery is a very common cause for a flood of seemingly unrelated codes on an E46, including the specific P1340 'Misfire During Start' definition used by BMW.

Lesson: On BMWs of this era, if you get P1340 plus a host of other electrical and misfire codes, test the battery and charging system first. A weak battery causes low cranking speed and voltage drops that the ECU interprets as misfires or sensor failures.

2005 Ford Falcon (BA) with multiple VCT codes

Owner was getting P1340 along with a full set of VCT (Variable Cam Timing) codes like P1381, P1383, etc. The car ran poorly.

Outcome: The actual solution was discovered by unplugging the main ECU (PCM) connector and finding corrosion from moisture. After cleaning the pins and connectors with compressed air and re-seating them with dielectric grease, the codes were resolved.

Lesson: In humid climates or on specific models like the Ford Falcon, electrical connector corrosion is the root cause. Before replacing expensive components, perform a thorough visual inspection of major harness and ECU connectors for any signs of moisture or corrosion.

2001 Audi A6 2.7T with persistent P1340 and P0300

After the car sat for three weeks, it developed a misfire. The owner replaced coils, plugs, and a faulty ICM. The misfire was fixed, but a P1340 code appeared. The owner then replaced the crankshaft position sensor, but the code remained.

Outcome: The owner's next step was to inspect the mechanical timing, specifically the chain and tensioner pads on Bank 1, suspecting a mechanical issue was the true cause of the correlation fault.

Lesson: A P1340 code that appears after other repairs and persists after replacing the indicated sensor points to a deeper mechanical timing issue or an incorrect initial diagnosis. Don't keep replacing sensors; move on to verifying mechanical timing.

How to Prevent This Code From Triggering

• Perform regular oil changes with high-quality, manufacturer-spec oil (Every 5,000-7,500 miles, or as per owner's manual.) — Clean, correct-viscosity oil is critical for lubricating timing chain components and ensuring proper function of hydraulic tensioners and VVT systems. Degraded or low-level oil accelerates chain stretch and tensioner failure.
• Replace timing belt at manufacturer's recommended interval (Typically every 60,000 to 100,000 miles (vehicle specific)) — Timing belts are a wear item. Replacing them proactively prevents them from slipping a tooth or breaking, which causes a P1340 code at best and catastrophic engine damage at worst.
• Avoid aggressive driving and excessive high-RPM operation (Daily habit) — Hard acceleration and frequent redlining put significant stress on the timing chain and tensioners, accelerating wear and the likelihood of stretching. Smoother driving habits prolong the life of timing components.
• Periodically inspect and clean major electrical connectors (Every 30,000 miles or during major service) — In humid or salty environments, moisture gets into main harness or ECU connectors, causing corrosion that leads to phantom codes like P1340. A quick inspection and application of dielectric grease prevents this.

Frequently Asked Questions

What are the most common misdiagnosis mistakes for P1340?

The biggest mistake is immediately replacing the camshaft sensor without a full diagnosis. Technicians often find the actual problem is damaged wiring, a corroded ECU connector, or a mechanical timing issue. Always test the circuit and check live data for cam/crank correlation before replacing parts.

Can I use a cheaper aftermarket sensor to fix P1340?

Do not use cheap aftermarket sensors for this code. Real-world accounts show these sensors are frequently dead-on-arrival or fail within weeks. Invest in an OEM or top-tier supplier part (like Bosch or Denso) to ensure the repair lasts.

Can I fix a P1340 code myself?

You can fix this yourself if the cause is an easily accessible camshaft sensor or a simple wiring issue. Stop DIYing and go to a shop if the cause is a stretched timing chain, an internal engine issue, or requires an oscilloscope for diagnosis. Timing jobs require specialized tools and carry a high risk of engine damage if done incorrectly.

What's the difference between a P1340 and a P0340?

P0340 is a generic OBD-II code for a camshaft sensor 'A' circuit malfunction. P1340 is a manufacturer-specific code that points to a more precise issue. Depending on the brand, P1340 indicates a correlation error between two sensors, a fault in the 'B' sensor circuit, or a startup misfire.

How much does it cost to diagnose a P1340 code?

Most repair shops charge a diagnostic fee ranging from $120 to $200. This fee covers an initial scan and an hour of testing, and is usually applied to the total repair cost if you proceed with the work.

Will a bad battery cause a P1340 code?

On most cars, a bad battery will not cause this code. However, on BMWs where P1340 means 'Misfire During Start', a weak battery causing slow cranking speed directly triggers the code.

Can a bad oil change cause P1340?

Yes, low oil levels or incorrect viscosity directly affect oil-pressure-driven variable valve timing (VVT) systems. This causes the camshafts to fall out of phase with the crankshaft, triggering a P1340 correlation code. Always verify oil level and condition first.

The car throws a P1340 code but seems to run fine. What's wrong?

This happens when the fault is intermittent or in its early stages. The ECU detected a brief loss of signal or a minor timing deviation that hasn't yet caused severe drivability issues. Treat this as an early warning and diagnose it before the engine stalls in traffic.

What happens if I don't fix code P1340?

Ignoring P1340 guarantees poor performance and fuel economy. You risk the engine stalling in traffic, destroying the catalytic converter from misfires ($1,200-$2,800 repair), or suffering complete engine failure if a timing chain breaks.

How do I clear a P1340 code?

Clear the code using an OBD-II scanner or by disconnecting the car's battery for 15 minutes. If the underlying problem remains, the code returns immediately once the ECU runs its diagnostic checks.

Key Takeaways

• Always look up the exact P1340 definition for your vehicle make, as it means a timing correlation issue on a VW but a startup misfire on a BMW.
• Check live data PIDs, such as VW's Measuring Block 093, to instantly determine if the fault is a failed sensor or a $2,000 mechanical timing chain issue.
• Inspect the main ECU connectors for corrosion and verify engine oil levels before replacing any sensors, as these frequently trigger false P1340 codes.
• Stop driving immediately if P1340 is accompanied by an audible engine rattle, as this indicates a failing timing chain tensioner that will destroy the engine if it breaks.
• Expect to pay $160 to $350 for a simple camshaft sensor replacement, but budget over $1,500 if diagnostics point to a stretched timing chain.