P0301 on 2012-2017 Toyota Camry Hybrid: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2012-2017 Toyota Camry Hybrid

The 2AR-FXE engine in the Camry Hybrid is known for its reliability, and a P0301 code is typically straightforward. Unlike some direct-injection engines, this port-injected, Atkinson-cycle engine is less prone to severe carbon buildup on intake valves causing misfires. The most common culprits are simple ignition components like coils and spark plugs, which are easily accessible on top of the engine. The hybrid system's frequent engine start-stop cycles can place different wear patterns on ignition components compared to a non-hybrid vehicle.

Generation note: The 2012-2017 Toyota Camry Hybrid is part of the XV50 generation. This generation received a major facelift for the 2015 model year, but the 2AR-FXE engine and its core components related to this code remained the same. The diagnostic process is identical for all years in this range.

Symptoms You May Notice

• Rough or shaky idle, which may be more noticeable when the gasoline engine kicks in
• Hesitation or stumbling during acceleration
• Flashing or solid Check Engine Light
• Noticeable loss of power, especially under heavy acceleration or high speeds.
• Reduced fuel economy
• A knocking sound on cold starts, which could be related to other issues but sometimes accompanies misfire conditions.

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability Ignition coils are a common wear item on most modern engines, including the 2AR-FXE. Heat cycles and high voltage eventually cause the internal windings to fail. This is the most common cause of a single-cylinder misfire.
   How to confirm: Swap the ignition coil from cylinder 1 with the coil from cylinder 2. Clear the codes and drive. If the code changes to P0302 (Cylinder 2 Misfire), the coil is faulty. This is the definitive DIY diagnostic step. 🎬 See how to perform this coil swap diagnostic on your Camry.
   Typical fix: Replace the faulty ignition coil. It is held in by a single 10mm bolt. 🎬 Watch: Step-by-step guide to replacing your coils and spark plugs. It's often recommended to replace the spark plug at the same time.
   Est. part cost: $40-$120
2. Worn or Fouled Spark Plug 🔴 High Probability Spark plugs have a finite service life. Toyota recommends replacement at 120,000 miles, but they can fail sooner, causing a weak or inconsistent spark. A cracked porcelain insulator or excessive electrode wear are common failure modes.
   How to confirm: After ruling out the coil, remove the spark plug from cylinder 1. Inspect it for wear, oil fouling, or carbon deposits. Compare it to the other plugs. A cracked insulator can be a dead giveaway. Also check for oil in the spark plug tube, which indicates a leaking valve cover gasket (a separate issue that can cause misfires).
   Typical fix: Replace the spark plug. It's recommended to replace all four spark plugs at the same time with the correct type (Iridium Long Life) for even performance and to prevent future issues. Always torque to spec (around 15-22 lb-ft for this engine).
   Est. part cost: $15-$30 per plug
3. Clogged Fuel Injector 🟡 Medium Probability While reliable, fuel deposits can accumulate over time, restricting fuel flow to a specific cylinder, leading to a lean misfire. This is less common than ignition issues but a definite possibility at higher mileage.
   How to confirm: This is more difficult to diagnose. A professional can perform a fuel injector balance test. A DIY method is to listen to the injector with a mechanic's stethoscope to ensure it's clicking. Swapping injectors between cylinders is possible but more involved than swapping coils.
   Typical fix: Replace the faulty fuel injector. Sometimes a professional fuel system cleaning can resolve minor clogs. 🎬 Watch: A simple DIY method for cleaning your fuel injectors.
   Est. part cost: $70-$200
4. Intake Manifold Gasket Leak ⚪ Low Probability The intake manifold gasket can become brittle with age and develop a vacuum leak near the cylinder 1 runner, introducing unmetered air and causing a lean misfire. This can sometimes be accompanied by a high or rough idle.
   How to confirm: With the engine running, spray a small amount of brake cleaner or starting fluid near the intake manifold runner for cylinder 1. If the engine RPM changes, a leak is present. A professional smoke test is a more definitive and safer method.
   Typical fix: Replace the intake manifold gaskets.
   Est. part cost: $20-$50

Rare But Worth Checking

• Low Engine Compression: This indicates a more serious mechanical engine problem, such as worn piston rings, a burnt valve, or a leaking head gasket. A compression test is needed to confirm. While the 2AR-FXE is generally robust, head gasket issues are not unheard of at very high mileage, especially if the engine has been overheated.
• Wiring Harness Issue: The wiring or connector to the ignition coil or fuel injector for cylinder 1 could be damaged or have a loose connection, causing an intermittent misfire. Check for rodent damage or chafing.
• Engine Control Module (ECM) Issue: In very rare cases, the driver circuit within the ECM that controls the ignition coil for cylinder 1 can fail. This is a last-resort diagnosis after all other possibilities have been exhausted.

Diagnosis Steps

1. Read the code with an OBD-II scanner and confirm P0301 is present. Note any other codes and freeze frame data, which shows engine conditions when the code was set.
2. Identify cylinder 1. On the 2AR-FXE, it is the cylinder closest to the drive belts on the passenger side of the vehicle.
3. Swap the ignition coil from cylinder 1 to cylinder 2. Clear the codes, drive the vehicle until the check engine light returns, and re-scan.
4. If the code is now P0302, the ignition coil from cylinder 1 is bad and must be replaced.
5. If the code remains P0301, swap the spark plug from cylinder 1 to cylinder 2. Clear, drive, and re-scan.
6. If the code is now P0302, the spark plug from cylinder 1 is bad. It is best practice to replace all four plugs.
7. If the code remains P0301, the issue is likely with the fuel injector, wiring, or a mechanical problem. Inspect the injector wiring and listen for operation with a stethoscope.
8. Check for oil contamination in the spark plug tube of cylinder 1. If oil is present, the valve cover gasket and spark plug tube seals need to be replaced.
9. Perform a compression test to rule out internal engine mechanical issues like a bad valve or head gasket.
10. If compression is good, consider a vacuum leak at the intake manifold and perform a smoke test to confirm.

Parts You'll Likely Need

• Ignition Coil (Coil-on-Plug) (OEM #90919-02258) — This is the most frequent cause of a single-cylinder misfire on this engine due to wear and tear from heat and high voltage.
  Trusted brands: Denso (OEM), NGK, Delphi
  OEM price range: $90-$130
  Aftermarket price range: $40-$80
• Iridium Spark Plug (OEM #90919-01253 (Denso SK16HR11)) — Spark plugs are a routine maintenance item and a worn electrode or cracked insulator will cause a misfire. The OEM Denso SK16HR11 is an Iridium Long Life plug.
  Trusted brands: Denso (SK16HR11), NGK (ILFR5T11)
  OEM price range: $20-$30
  Aftermarket price range: $15-$25

Technical Service Bulletins (TSBs) & Recalls

• T-SB-0148-19 / L-SB-0044-19: While not for the Camry specifically, these TSBs for other Toyota/Lexus models with misfire codes sometimes point to an ECM software update being needed in conjunction with an ignition coil replacement. This is a rare scenario for the Camry but worth noting if basic parts replacement doesn't solve the issue.
• T-SB-0116-15 Rev: This bulletin for other Toyota hybrid models (Prius V) notes that a P0301 misfire can occur during light acceleration while the Exhaust Gas Recirculation (EGR) system is active, which may require replacing the intake manifold.
• T-SB-0147-16: A manufacturer service bulletin for the Prius describes a vibration due to rough idle and/or tapping noise from the HV transaxle at cold start, which may illuminate the check engine light with DTC P0301 and other misfire codes.

Platform-Specific Known Issues

• While the 2AR-FXE is not known for the severe oil consumption of the earlier 2AZ-FE engine, some consumption can occur at high mileage, especially with extended oil change intervals. This can lead to fouled spark plugs over time.
• The hybrid system's operation means the engine may not run continuously, which can make it slightly trickier to diagnose misfires that only occur under specific load or temperature conditions.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance — expected: 11.6 to 12.4 Ω at 20°C (68°F). Failure: A reading outside of this range indicates a faulty injector.
• Ignition Coil Primary Resistance (Cold) — expected: 0.36 - 0.55 Ω. Failure: Resistance outside this range suggests a faulty coil.
• Ignition Coil Secondary Resistance (Cold) — expected: 9.0 - 15.4 kΩ. Failure: Resistance outside this range suggests a faulty coil.
• Techstream Data List - Misfire RPM — expected: Displays the engine RPM at which the misfire was first detected.. Failure: This value, along with Misfire Load, helps replicate the conditions that caused the code.
• Techstream Data List - Misfire Load — expected: Displays the calculated engine load when the misfire was first detected.. Failure: This value, along with Misfire RPM, helps replicate the conditions that caused the code.

Hidden / Shadow Codes Worth Checking

• Mode $06, Test ID $81, Component ID $01-$04: Mode $06 provides access to non-continuous monitor test results. For misfires, it logs misfire counts per cylinder even if they aren't high enough to set a CEL. Component IDs $01, $02, $03, and $04 correspond to cylinders 1, 2, 3, and 4 respectively. A high count for Component ID $01 would confirm the P0301. (see via An advanced OBD-II scanner or Toyota Techstream software capable of displaying Mode $06 data.)

Scan Tool Commands That Help

• Toyota Techstream: Misfire Count (CYL #1) — Use this function in the Data List to see a live count of misfire events on cylinder 1. This is more accurate than the generic OBD-II data stream and can help confirm an intermittent misfire that doesn't immediately set a code.
• Toyota Techstream: Active Test: Control the Injection Volume for each Injector — This allows a technician to individually command each fuel injector to operate. By listening for a click or using a scope, one can confirm if the injector is responding to ECM commands, helping to isolate a fuel vs. spark issue.
• Toyota Techstream: Active Test: Check Mode — Switching the ECM to Check Mode increases its sensitivity for detecting misfires. This is useful for confirming an intermittent misfire issue during a test drive under the conditions noted in the freeze frame data.

Wiring & Ground Locations

• Cylinder 1 Ignition Coil Connector — On top of the valve cover, first coil from the passenger side (belt side) of the engine.. This 4-pin connector provides power, ground, and trigger/feedback signals to the coil. Pin 1: IGF (Ignition Confirmation), Pin 2: IGT (Ignition Trigger), Pin 3: Ground, Pin 4: B+ (12V Power). A damaged pin or wire here directly causes a P0301.
• Engine Ground (Valve Cover) — There are two main engine harness grounding points on top of the valve covers, bolting the harness ground to the engine itself.. A loose or corroded ground at these points can cause a weak or inconsistent spark across all cylinders, but can sometimes manifest as a single-cylinder misfire under specific loads due to voltage drop. This is a commonly overlooked cause for intermittent ignition issues.
• EA1 Connector — Located in the left kick panel, connecting the instrument panel wire and the engine room main wire.. This is a major junction connector. While not a primary suspect, corrosion or a loose pin in this area can cause various electrical issues, including intermittent power to the ECM or ignition system components.

OEM Part Supersession History

• 90919-02252 → 90919-02258 — Standard part revision for improved reliability or manufacturing process change.
  Heads up: The new part number 90919-02258 is a direct replacement for 90919-02252 and is fully compatible.

Model Year Variations Within This Range

• 2012-2014 vs 2015-2017: The Camry Hybrid received a significant facelift for the 2015 model year, including new exterior styling and interior updates. However, the core 2AR-FXE engine and its ignition/fuel systems remained unchanged. The diagnostic procedure for a P0301 code is identical across the entire 2012-2017 range.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Brake Booster / Actuator Assembly Failure 🔴 High — Common enough to prompt a warranty enhancement program (ZKK) and multiple TSBs. Can occur at various mileages. (Ref: TSB-0130-19, Warranty Enhancement ZKK. Can cause DTCs like C1391, C1252, C1256.)
• Torque Converter Shudder 🟠 Medium — A known issue for 2012-2017 models, often appearing as a vibration or shudder at steady speeds (around 35-45 mph). (Ref: TSB-0158-17 suggests a transmission fluid flush as an initial fix, but converter replacement may be needed.)
• HV Battery Cooling Fan Clogging 🟡 Low — Dust and debris can clog the hybrid battery cooling fan filter over time, reducing cooling efficiency and potentially shortening battery life. (Ref: TSB T-SB-0087-13 Rev recommends inspection and cleaning of the fan and filter.)
• Minor Oil Consumption 🟡 Low — While much improved over the previous 2AZ-FE engine, the 2AR-FXE can still consume some oil, especially with high mileage or 10,000-mile oil change intervals. Not typically a critical failure but requires monitoring oil levels.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this repair, using a used part is generally only recommended for the ignition coil. It's a simple, external component that is easy to swap. A used fuel injector is a riskier choice due to potential for internal clogging.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For an ignition coil, inspect the plastic housing for any cracks or signs of melting.
• Check the rubber boot for tears, swelling, or brittleness.
• Ensure the electrical connector pins are clean and free of corrosion.
• Ask for the donor vehicle's mileage; a lower-mileage part is always preferable.

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

• Engine Control Module (ECM) - Due to programming and security synchronization, a used ECM is often more trouble than it's worth and should be sourced new from a dealer if required.

Aftermarket brands forum-validated for this vehicle:

• Denso (This is the Original Equipment Manufacturer for the ignition coils and spark plugs)
• NGK (A highly reputable OEM supplier for ignition components)

Brands owners have reported issues with on this vehicle:

• Unnamed, no-brand ignition coils from online marketplaces. While the initial cost is low, they have a very high failure rate and can cause further diagnostic confusion.

Real Owner Stories

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

Documented NHTSA Reports

Related OBD-II Codes

• P0302 — This code indicates a Cylinder 2 misfire; it is used during the diagnostic process to confirm a faulty ignition coil or spark plug by swapping parts from Cylinder 1 to Cylinder 2.
• C1391 — A code related to Brake Booster / Actuator Assembly failure, which is a known high-severity issue for this vehicle generation (2012-2017).
• C1252 — Associated with the Brake Booster / Actuator Assembly failure and the Warranty Enhancement Program ZKK for this model range.
• C1256 — Another code frequently seen alongside brake actuator malfunctions, which are common enough on this platform to prompt specific TSBs like TSB-0130-19.

Frequently Asked Questions