P0340 on 2014-2018 Ram 3500: Camshaft Position Sensor Circuit Causes and Fixes

What's Unique About the 2014-2018 Ram 3500

For this generation of Ram trucks, Chrysler (now Stellantis) issued specific Technical Service Bulletins (TSBs) regarding code P0340. TSBs #68080819A and #05149141A instruct dealership technicians to contact a specific factory engineer before replacing the camshaft position sensor. This is highly unusual and strongly implies that the root cause is often not a simple sensor failure, but rather a more complex issue like wiring problems or other factors that lead to misdiagnosis. Owner forums confirm this, with many users going through multiple sensors before finding the true cause, which is often a damaged wire or a faulty connector pigtail.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light is on
• Difficulty starting the engine, or long crank times.
• Engine stalls, sometimes intermittently, especially when coming to a stop.
• Engine cranks but will not start.
• Rough idle
• Hesitation or lack of acceleration.
• Reduced fuel economy.
• Transmission may not shift properly or go into "limp mode".

Most Likely Causes

1. Wiring Harness or Connector Damage 🔴 High Probability The engine bay environment exposes wiring to heat, vibration, and potential chafing, which can damage the circuit over time. The wiring for the camshaft sensor is particularly susceptible. Forum users frequently report finding wires that have rubbed against the engine block or other components, causing a short.
   How to confirm: Visually inspect the entire wiring harness for the camshaft position sensor, from the sensor itself back to the main loom and towards the PCM. Pay close attention to where the harness may contact other parts. Look for frayed wires, melted insulation, corrosion in the connector, or loose pins. Wiggle the connector and wiring with the engine running to see if it causes the engine to stumble or the code to appear.
   Typical fix: Repair the damaged section of wire or replace the connector pigtail. In some cases, a new engine wiring harness is required if the damage is extensive. One owner on RamForum.com had a dealer replace the pigtail wiring all the way back to the PCM to resolve the issue after multiple failed attempts.
   Est. part cost: $10-$40 for a pigtail, $1200+ for dealer harness repair.
2. Faulty Camshaft Position Sensor (CMP) 🟡 Medium Probability Sensors can fail over time due to internal electronic faults or heat cycles. However, this is often incorrectly diagnosed as the primary cause. Many owners report that replacing the sensor, even with an OEM part, does not fix the code, suggesting the original sensor was not the problem. Using aftermarket sensors is highly discouraged by forum members, as they seem to fail quickly or not work at all.
   How to confirm: After confirming the wiring is good, the sensor itself can be tested. The best method is using an oscilloscope to check for a proper square wave signal while cranking the engine. A simpler method is to check for the 5V reference voltage and a good ground at the connector with a multimeter.
   Typical fix: Replace the camshaft position sensor with a high-quality OEM Mopar part.
   Est. part cost: $25-$215
3. Mechanical Timing Issue ⚪ Low Probability On higher mileage engines, a stretched timing chain (HEMI engines) or a worn timing gear (Cummins) can cause the camshaft and crankshaft correlation to be off, triggering the code. This is a less common but more severe problem.
   How to confirm: This is an advanced diagnosis. It may involve checking for slack in the timing chain or comparing the cam and crank sensor signals on an oscilloscope to check for correlation. This issue is often accompanied by other codes like P0016.
   Typical fix: Replace the timing chain, gears, and tensioners. On a HEMI, this can also involve replacing the cam phaser.
   Est. part cost: $400-$1700+

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This is rare and should only be considered after all other possibilities (sensor, wiring, timing) have been exhaustively ruled out. One forum member replaced the PCM, but the code returned, indicating it was not the root cause.
• Damaged Tone Ring: The reluctor or tone ring on the camshaft that the sensor reads can become damaged, loose, or have debris on it, causing an erratic signal. This usually requires significant disassembly to inspect.
• Weak Battery or Faulty Alternator: A weak or dying battery, or a faulty alternator causing voltage fluctuations, can trigger a P0340 code. The PCM is sensitive to voltage, and a low-voltage condition during cranking can cause a spurious sensor circuit code to be set. One user on RamForum.com noted the problem started after their battery died.
🎬 See how a real-world P0340 electrical issue was diagnosed and fixed.

Diagnosis Steps

1. Scan for all stored trouble codes. Note any other codes that are present, especially P0344 or P0016, as they can help pinpoint the cause.
2. Check Battery Health. Ensure the battery is fully charged and the alternator is functioning correctly. A weak battery can cause spurious electrical codes.
3. Perform a thorough visual inspection of the camshaft position sensor, its connector, and the entire length of its wiring harness. Look for any signs of damage, melting, chafing against the engine, or corrosion. Wiggle the harness while the engine is running to check for intermittent faults.
4. With the key on and engine off, use a multimeter to check for the correct reference voltage (usually 5V) and a good ground at the sensor connector.
5. If power and ground are good, the best diagnostic step is to use an oscilloscope to view the sensor's output signal while cranking or running the engine. It should be a clean, consistent square wave. 🎬 Watch: A professional walkthrough of the camshaft circuit diagnostic process. An intermittent or missing signal with good power/ground points to a bad sensor.
6. If the wiring is confirmed to be good and you suspect the sensor, replace it with an OEM Mopar part ONLY. Aftermarket sensors are a common source of continued problems.
7. If the signal is good but the code persists, or if you also have a P0016 code, investigate potential mechanical timing issues (timing chain slack, damaged tone ring).
8. As a final step, if all else fails, consider the possibility of a faulty PCM, but exhaust all other options first.

Parts You'll Likely Need

• Camshaft Position Sensor (OEM #For 6.7L Cummins: Mopar 68526830AB (replaces 68526830AA, 5179099AB). For 5.7L & 6.4L HEMI: Mopar 5149054AC (replaces 5149054AB).) — While often misdiagnosed, a failed sensor is still a common cause for this code after wiring issues are ruled out. Using the official Mopar part is highly recommended to avoid repeat failures.
  Trusted brands: Mopar (Recommended), Bosch, NTK, Duralast
  OEM price range: $50-$100 for HEMI, $140-$215 for Cummins.
  Aftermarket price range: $25-$100
• Camshaft Position Sensor Connector Pigtail — The connector itself or the wires immediately attached to it are a frequent failure point due to heat and vibration. Replacing the pigtail is a common repair.
  Trusted brands: Mopar, Dorman, Standard Motor Products
  OEM price range: $20-$50
  Aftermarket price range: $10-$30

Related Codes That Often Appear With This One

• P0344 — This code means 'Camshaft Position Sensor 'A' Circuit Intermittent,' which points directly to a wiring issue, a failing sensor, or a loose connection. It is specifically mentioned alongside P0340 in TSB #68080819A.
• P0335 — This is the code for the Crankshaft Position Sensor. Since the cam and crank sensors work together for engine timing, a fault in one system can sometimes cause the computer to flag the other, or a wiring issue may affect both circuits.
• P0016 — This code indicates a 'Crankshaft Position - Camshaft Position Correlation' error. If you see P0340 along with P0016, it strongly suggests a mechanical timing issue, like a stretched timing chain or slipped tone ring, rather than an electrical fault.

Technical Service Bulletins (TSBs) & Recalls

• 68080819A: 'Camshaft Position Sensor If replacing a camshaft position sensor for P0340 and/or P0344 fault codes, please review information below and contact Andrew Action...'
• 05149141A: 'Camshaft Position Sensor If replacing a camshaft position sensor for P0340, P0344, P0345, P0349, P0365, P0369, P0390 or P0394 fault codes, please review information below and contact Tom Nies...'

Platform-Specific Known Issues

• TSB #68080819A and #05149141A: These bulletins from 2015 specifically address fault codes P0340 and P0344. They instruct technicians to contact a specific factory representative before replacing the camshaft position sensor, indicating a known issue with misdiagnosis where the sensor itself is not the true cause of the fault.
• HEMI vs. Cummins Differences: While both engine families can experience this code, the physical location of the sensor and common wiring chafe points differ. On the 6.7L Cummins, the sensor is on the driver's side of the block, often requiring removal of the PCM for access. On HEMI engines, it is more accessible on the front of the engine under the alternator.

Mechanic-Grade Diagnostic Values

• Camshaft Sensor 5V Supply — expected: Approximately 5.0 volts. Failure: Voltage below 4.5 volts or no voltage indicates an open/short in the supply circuit from the PCM.
• Camshaft Sensor Ground Circuit Resistance — expected: Below 5.0 ohms. Failure: Resistance higher than 5.0 ohms indicates a poor ground connection.
• Camshaft Sensor Signal Wire (Sensor Disconnected) — expected: Approximately 5.0 volts. Failure: No voltage may indicate an issue with the PCM or wiring.
• Camshaft Sensor Signal Waveform (Oscilloscope) — expected: A clean, consistent square wave that switches between approximately 0V and 5V as the engine is cranked.. Failure: A missing, intermittent, or noisy waveform indicates a faulty sensor or wiring issue.

Scan Tool Commands That Help

• wiTECH (Chrysler Dealer Tool): PCM Software Reflash — A related TSB (18-010-13) for 2011-2012 models indicates that if P0340 sets at a low engine speed (500 RPM or less according to freeze frame data), a PCM software update may be the required fix to correct faulty logic. This could be relevant if the code only appears during startup.

Wiring & Ground Locations

• Potential Harness Chafe Point — On the driver's side of the transmission bell housing, where the main harness (potentially near connector C108) passes by a metal engine grounding strap.. Engine vibration can cause the grounding strap to rub through the harness loom and short one of the sensor wires to ground, causing an intermittent or constant P0340 code. This is a hidden damage point that is not easily visible.
• Camshaft Position Sensor (6.7L Cummins) — Driver's side of the engine block, below the CP3 injection pump and above the power steering pump.. This is the physical location of the sensor. Access is tight and may require unbolting the PCM (four 10mm bolts) for clearance. The sensor itself is held by a 5mm hex bolt.
• Camshaft Position Sensor (5.7L/6.4L HEMI) — Front of the engine, located underneath the alternator, held by a 10mm bolt.. This is the physical location of the sensor. On HEMI engines, several sensors, including the cam sensor, crank sensor, and others, may share the same ground circuit from the PCM.
• PCM (Powertrain Control Module) — Mounted to the firewall on the passenger side of the engine bay.. This is the location of the engine computer. All sensor wiring terminates here. Accessing its connectors is necessary for advanced circuit testing.

Real Owner Repair Stories

• Rapid Car Care LLC on YouTube (Dodge Ram 5.7L HEMI (year not specified, but 4th gen body style)) — Crank no-start, P0340 (Cam Sensor) and P0129 (Barometric Pressure) codes, red lightning bolt on dash.
  ❌ Tried (didn't work) Replacing the camshaft position sensor., Replacing the barometric pressure sensor.
  ✅ What actually fixed it Replacing the Crankshaft Position Sensor. The video notes that the cam sensor, crank sensor, throttle body, barometric pressure sensor, and oil pressure switch all share the same ground circuit from the PCM, and the failing crank sensor was causing the other codes.
• User on DodgeForum.com (3rd Gen Ram (year not specified)) — ETC light, engine light, rough idle, no throttle response, codes P0340 and P0562 (low voltage).
  ❌ Tried (didn't work) Replacing Electronic Throttle Control., Replacing Camshaft Position Sensor., Replacing battery., Replacing Crankshaft Position Sensor., Testing all associated wiring for continuity (all tested good).
  ✅ What actually fixed it Replacing the EGR valve. After finding an obscure forum topic suggesting the EGR valve could be the cause, the owner replaced it, performed a PCM reset, and all codes and symptoms were resolved.
• User jkey63876 on RamForum.com (2011 Ram 1500 5.7L 4x4 with 196k miles) — Check engine light with P0340, truck enters limp mode (won't shift over 4th gear), but no stalling or rough idle.
  ❌ Tried (didn't work) Replacing camshaft sensor., Replacing crankshaft sensor., Dealer replaced the camshaft phaser ($1700).
  ✅ What actually fixed it The thread ended without a final confirmed fix, but serves as a strong warning that replacing the cam/crank sensors and even the expensive cam phaser may not solve the problem, pointing towards a complex wiring or PCM issue.

When the Usual Fixes Don't Work

• In several documented cases, replacing the camshaft position sensor, even with an OEM part, did not resolve the P0340 code. One owner had a dealer replace the cam sensor, crank sensor, and ultimately the cam phaser at a cost of over $1700, only for the code to return immediately, strongly suggesting the root cause was an elusive wiring or module issue. Another owner fixed a persistent P0340 by replacing the crankshaft position sensor, which had not set its own trouble code, because it shared a faulty ground circuit with the cam sensor. These experiences underscore the TSBs that warn against immediate sensor replacement and point to the circuit itself as the primary area for diagnosis.

OEM Part Supersession History

• 68526830AA, 5179099AB, 5179099AA, 5093101AA → Mopar 68526830AB — Part has been revised and updated by the manufacturer over time.
  Heads up: This part is for the 6.7L Cummins engine and serves as both the camshaft and crankshaft position sensor.
• 5149054AB → Mopar 5149054AC — Part has been revised by the manufacturer.
  Heads up: This part is for the 5.7L and 6.4L HEMI engines.