P0301 on 2006-2012 Toyota RAV4 3.5L V6: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2006-2012 Toyota RAV4

The 2GR-FE 3.5L V6 in the RAV4 is a very reliable engine, but like any modern engine, its coil-on-plug ignition system is a common failure point as the vehicle ages. For this specific engine in a transverse (sideways) layout, cylinder 1 is on the rear bank against the firewall, making it more difficult to access than the front cylinders. While ignition components are the primary culprits, a notable number of owners have resolved a persistent P0301 code by replacing a faulty PCV valve that caused oil to pool in the intake manifold near the cylinder 1 intake runner, fouling the plug.

Symptoms You May Notice

• Rough or shaky idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Solid or flashing Check Engine Light
• Smell of raw gasoline from the exhaust
• Hard starting after the code appears

Most Likely Causes

1. Failed Ignition Coil 🔴 High Probability Coil-on-plug systems are a common wear item. Heat cycles and vibration eventually cause the internal windings to fail. The rear bank coils, including cylinder 1, experience more heat soak which can shorten their lifespan. Toyotas are also known to be sensitive to non-OEM electronics, making a quality replacement important.
   How to confirm: Swap the ignition coil from cylinder 1 with one from an accessible front cylinder (e.g., cylinder 2). Clear the codes and drive. If the code changes to P0302, the coil is faulty.
   Typical fix: Replace the failed ignition coil. It is often recommended to replace all coils on the same bank, or all six, if they are original and high-mileage.
   Est. part cost: $70-$115 for one OEM-quality coil.
2. Worn or Fouled Spark Plug 🟡 Medium Probability Spark plugs are a routine maintenance item with a service interval of 120,000 miles. However, other issues like a leaking valve cover gasket or faulty PCV valve can foul the plug with oil, causing a misfire long before it's worn out.
   How to confirm: After ruling out the coil, remove the spark plug from cylinder 1. Inspect it for wear (eroded electrode), carbon fouling, or oil contamination. A Toyota technician on Reddit noted oil on the threads of rear bank plugs can be from minor, but common, valve cover gasket seepage.
   Typical fix: Replace the spark plug. It is best practice to replace all six spark plugs at the same time to ensure consistent performance, especially given the labor to access the rear bank.
   Est. part cost: $10-$20 per iridium spark plug.
3. Clogged or Failed Fuel Injector ⚪ Low Probability Fuel injectors can become clogged with deposits over time, leading to a poor spray pattern or insufficient fuel delivery, causing a lean misfire. This is more common on higher mileage vehicles.
   How to confirm: This is more complex. After ruling out ignition, you can swap the fuel injector from cylinder 1 with one from another cylinder. If the misfire code follows the injector (e.g., moves to P0302 after swapping with cylinder 2), the injector is the cause. This requires removing the fuel rail.
   Typical fix: Replace the faulty fuel injector. It's also recommended to replace the O-rings and seals for the other injectors on that fuel rail. Some owners have had success with professional injector cleaning services.
   Est. part cost: $80-$150 for one OEM injector, remanufactured units are cheaper.

Rare But Worth Checking

• Faulty PCV Valve: A stuck-open PCV valve can allow excessive oil vapor into the intake manifold. On the 2GR-FE, the intake plenum design can cause this oil to preferentially pool near the cylinder 1 intake runner, fouling the spark plug and causing a P0301. A user on the 'ToyotaNation' forum provided a detailed account of resolving a persistent P0301 by replacing the PCV valve after new plugs and coils failed to fix it. This is an inexpensive part worth checking.
• Intake Manifold Gasket Leak: A vacuum leak from a failed intake manifold gasket near the cylinder 1 runner can lean out the air-fuel mixture and cause a misfire. This is often diagnosed with a smoke test. The gasket must be replaced anytime the plenum is removed for service.
• Low Engine Compression: A serious mechanical issue like a burnt valve, worn/broken piston rings, or a head gasket failure can cause a loss of compression in cylinder 1. A compression test is required to diagnose this. One owner on a forum with a high-mileage (253k miles) RAV4 V6 ultimately found their P0301 was caused by a broken compression ring in cylinder 1.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0301 is present.
2. Note if the Check Engine Light is solid or flashing. A flashing light indicates a severe misfire that can damage the catalytic converter.
3. Identify Cylinder 1. On the 2GR-FE in the RAV4, the cylinders are numbered 1-3-5 on the rear bank (against the firewall, from passenger to driver side) and 2-4-6 on the front bank. Cylinder 1 is on the rear bank, passenger side.
4. Swap the ignition coil from Cylinder 1 with the coil from Cylinder 2 (front bank, passenger side). This is the easiest diagnostic step.
5. Clear the codes and drive the vehicle until the Check Engine Light returns.
6. Re-scan for codes. If the code is now P0302, the ignition coil you moved is faulty. Replace it with a quality OEM or Denso part. Torque the coil bolt to 7 ft-lbf (10 Nm).
7. If the code remains P0301, the coil is likely good. The next step is to inspect the spark plug. This typically requires removing the upper intake manifold (plenum) to access the rear bank. Note: Some skilled mechanics have demonstrated methods to do this without removing the plenum, but it is very tight.
8. When removing the plenum, you must replace the intake plenum gaskets (a set of 3) and the throttle body gasket.
9. Once accessible, remove the spark plug from Cylinder 1. Inspect for wear, fouling, or damage. It's highly recommended to replace all 6 spark plugs (Denso FK20HR11 is the OEM spec) if they are due. Torque new plugs to 15 ft-lbf (21 Nm).
10. Reassemble with the new gaskets. Torque the intake plenum bolts and nuts to 15 ft-lbf (21 Nm) in several passes.
11. If the problem persists with a new plug and known-good coil, inspect the PCV valve. If it's original or oily, replacement is a cheap and easy step.
12. If the code still remains P0301, the issue is likely deeper (fuel injector, wiring, or a mechanical compression issue) and may require professional diagnosis.

Parts You'll Likely Need

• Ignition Coil (OEM #90919-A2007 (superseded by 90919-A2013)) — This is the most frequent cause of a single-cylinder misfire on the 2GR-FE engine. The rear bank location of cylinder 1 makes it subject to high heat.
  Trusted brands: Denso, NGK, Toyota OE
  OEM price range: $90-$115
  Aftermarket price range: $40-$80
• Iridium Spark Plug (OEM #90919-01247 (Denso FK20HR11)) — Spark plugs are a maintenance item and can cause misfires when worn. Since accessing the rear bank requires significant labor, it's wise to replace all three rear plugs if you are replacing one.
  Trusted brands: Denso (FK20HR11), NGK (DILFR6D11)
  OEM price range: $15-$25
  Aftermarket price range: $10-$18
• Intake Plenum Gasket Set (OEM #17176-0P021) — This gasket must be replaced anytime the upper intake manifold (plenum) is removed to access the rear spark plugs or ignition coils. Reusing the old gasket will cause a vacuum leak.
  Trusted brands: Toyota OE, Fel-Pro
  OEM price range: $20-$30
  Aftermarket price range: $10-$20
• PCV Valve (OEM #12204-31040) — A cheap but critical part. A stuck PCV valve is a known, though less common, cause of P0301 on this engine due to oil being drawn into the intake manifold near cylinder 1.
  Trusted brands: Toyota OE
  OEM price range: $10-$25
  Aftermarket price range: $5-$15

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or affects other cylinders, a P0300 (Random/Multiple Cylinder Misfire) may be stored alongside P0301.
• P0303, P0305 — These codes indicate misfires on the same bank of cylinders (Bank 1, the rear bank). If multiple codes from the same bank appear, it could point to a shared issue like a clogged catalytic converter for that bank or a vacuum leak affecting all three cylinders.

Technical Service Bulletins (TSBs) & Recalls

• While no TSBs directly address the P0301 code specifically, a critical TSB/LSC for this engine is the VVT-i oil line replacement. Early 2GR-FE engines (2006-2009) used a rubber hose section that could rupture, causing rapid oil loss and catastrophic engine failure. Owners should verify if their vehicle has been updated to the all-metal line (P/N 15772-31030).

Platform-Specific Known Issues

• A 2010 RAV4 V6 owner on ToyotaNation forums ('2010 Limited 2gr-fe P0301 Misfire Code *Resolved*') detailed a lengthy battle with P0301. After replacing plugs and the coil with no su

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance — expected: 11.6 to 12.4 Ohms at 20°C (68°F). Failure: A reading significantly outside this range indicates a failed internal coil. An open circuit (infinite resistance) or a short (near zero resistance) confirms a bad injector.
• Ignition Coil Primary Resistance — expected: Approximately 0.4 to 0.6 Ohms. Failure: This value is very low and difficult to measure accurately with most multimeters. It is not a reliable test for DIY diagnosis.
• Ignition Coil Secondary Resistance — expected: Approximately 9.0 to 11.5 kOhms. Failure: A reading far outside this range can indicate a failed coil, but a coil can still be faulty even with correct resistance. Swapping coils remains the most reliable test.
• Techstream Live Data - Misfire Rate — expected: 0 counts at idle and under load. Failure: Any count incrementing on Cylinder 1 while driving or idling confirms an active misfire. This is more reliable than the standard data list under load.

Hidden / Shadow Codes Worth Checking

• Mode $06, Component ID $A2 (Cylinder 1 Misfire Data): This is not a DTC but a monitor within the OBD-II system that stores misfire counts for each cylinder from recent driving cycles. It can show misfires that haven't yet reached the threshold to trigger a P0301 code. (see via An advanced OBD-II scanner or Toyota Techstream software that can display Mode $06 data.)

Scan Tool Commands That Help

• Toyota Techstream: Active Test: Control the Injection Mode / Fuel Cut — After ruling out the ignition coil and spark plug, this test can confirm if the fuel injector is the problem. By commanding the fuel injector for cylinder 1 to shut off, you can observe the change in engine RPM. If there is no change in RPM when cylinder 1 is cut, it confirms that cylinder was not contributing power, pointing strongly to a fuel delivery or compression issue for that cylinder.
• Toyota Techstream: Misfire Monitor (Details) — This provides a more accurate and detailed history of misfire events than the standard live data list, especially for misfires that occur under load. It shows both a historical count (EWMA) and a current misfire rate, helping to pinpoint the problematic cylinder when the issue is intermittent.

Wiring & Ground Locations

• Cylinder 1 Ignition Coil Connector — On the ignition coil for cylinder 1, which is on the rear cylinder bank (against the firewall), passenger side.. This connector provides power, ground, and the trigger signal (IGT1) from the ECM. A corroded or loose pin can cause a misfire. Pin 1: IGT1 (Trigger from ECM), Pin 2: IGF1 (Ignition confirmation to ECM), Pin 3: Ground, Pin 4: +12V Power (from IG2 relay).
• Engine Harness Ground (Bank 1) — On the side of the rear cylinder head (Bank 1), typically under or near the throttle body assembly.. A poor ground connection at this point can cause erratic behavior for sensors and actuators on Bank 1, including the ignition coils and injectors. This can lead to intermittent misfires that are difficult to diagnose.
• ECM Connector C13 — At the Engine Control Module (ECM). The ECM location can vary; on earlier models it may be behind the glovebox, while on later models it's in the engine bay.. This connector contains the specific wires for the cylinder 1 ignition coil. Pin C13-2 is the IGF1 (confirmation) signal and Pin C13-6 is the IGT1 (trigger) signal. These pins can be back-probed to test for correct voltage signals from the ECM and coil.

Real Owner Repair Stories

• ToyotaNation Forum user '2010RAV4V6' (2010 Toyota RAV4 V6) — Flashing Check Engine Light, hesitation, hard starts, and P0301 code. Symptoms would temporarily disappear after disconnecting the battery but always returned.
  ❌ Tried (didn't work) Replaced spark plug in cylinder 1 (non-OEM), Replaced ignition coil on cylinder 1 (non-OEM), Swapped the original OEM coil from cylinder 6 to cylinder 1
  ✅ What actually fixed it The final fix was replacing the PCV valve. The user noticed a pool of oil in the intake manifold specifically around the cylinder 1 intake runner, which was fouling the plug. Replacing the faulty PCV valve resolved the oil intrusion and the P0301 code did not return.

OEM Part Supersession History

• 90919-A2007 → 90919-A2013 — Standard part revision and consolidation by the manufacturer.
  Heads up: None. 90919-A2013 is a direct, backward-compatible replacement for 90919-A2007 and other previous part numbers like 90919-A2002 and 90919-02251.

Model Year Variations Within This Range

• 2006-2008: Early 2GR-FE engines used a rubber VVT-i oil supply line that was prone to rupturing, causing rapid oil loss. This was subject to a recall and replaced with an all-metal line. While not a direct cause of P0301, a significant oil leak could lead to low oil levels, which can damage VVT gears and affect engine timing, potentially contributing to misfires.
• 2009-2012: For the 2009 model year, the RAV4 received a facelift and a new 2.5L 4-cylinder engine option. The 2GR-FE V6 remained largely unchanged, but these later models came from the factory with the updated all-metal VVT-i oil line, eliminating that specific failure point.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• VVT-i Oil Line Rupture 🔴 High — Common on early models (2006-2009) that have not had the updated part installed. Failure can occur without warning and lead to catastrophic engine failure from oil starvation. (Ref: Toyota issued a Limited Service Campaign (LSC) to replace the original rubber/metal hose with an all-metal line (Part No. 15772-31030).)
• Water Pump Failure 🔴 High — A well-documented issue on the 2GR-FE, especially on models approaching or exceeding 100,000 miles. Failure often begins as a slow leak of pink, dried coolant from the weep hole before progressing. (Ref: No official recall, but it is a widely acknowledged failure point. Proactive replacement is often recommended.)
• Intermediate Steering Shaft Clunk 🟡 Low — A common annoyance on 2006-2012 models, causing a clunking noise or binding feeling in the steering wheel at low speeds. (Ref: No recall, but the typical fix is lubrication or replacement of the intermediate shaft.)
• VVT-i Gear Rattle on Cold Start 🟠 Medium — Some higher-mileage V6 models may develop a brief, intense rattle from the engine on cold startups, pointing to wear in the VVT-i cam phasers.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: Used parts make sense for larger mechanical components like a complete cylinder head if a compression issue is found, as they are durable and expensive new. A used intake manifold could also be a cost-effective replacement if the original is damaged during service.

Donor-vehicle mileage cap: roughly under 100000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For ignition coils or injectors, ask for the mileage of the donor vehicle. Low-mileage parts are preferable.
• Check electrical connectors for any signs of cracking, brittleness, or corrosion.
• When buying a used engine component, look for signs of heavy oil leaking or sludge, which indicates poor maintenance.
• Ensure the part comes from a vehicle that was not in a major front-end collision.

OEM-only on this vehicle (don't cheap out):

• PCV Valve: This part is inexpensive and critical; aftermarket versions can have incorrect flow rates. Always use a Toyota OE part.
• Intake Gaskets: While quality aftermarket gaskets from brands like Fel-Pro are acceptable, the cost of Toyota OE gaskets is minimal and guarantees a perfect fit, which is critical to prevent vacuum leaks after a difficult job.

Aftermarket brands forum-validated for this vehicle:

• Ignition Coils: Denso, NGK. Denso is the original equipment manufacturer.
• Spark Plugs: Denso (FK20HR11), NGK (DILFR6D11). These are the OEM spec plugs.
• Fuel Injectors: Denso (OEM).

Brands owners have reported issues with on this vehicle:

• Unnamed or 'white box' ignition coils and sensors from online marketplaces. Forum users consistently report premature failure, poor fitment, and intermittent issues with these parts on Toyota's sensitive electronic systems.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0300 — Random or Multiple Cylinder Misfire Detected; often accompanies P0301 if the root cause (like a faulty PCV valve or lean condition) affects more than one cylinder.
• P0302 — Cylinder 2 Misfire; used during the diagnostic 'coil swap' procedure to confirm if a faulty ignition coil from Cylinder 1 is the cause of the misfire.
• P0303 — Cylinder 3 Misfire; another rear-bank cylinder that shares the same heat-soak environment and difficult access as Cylinder 1.
• P0305 — Cylinder 5 Misfire; located on the same rear bank as Cylinder 1, often sharing the same wear patterns for coils and spark plugs.

Frequently Asked Questions