P0346 on 2011-2013 Subaru Forester: Causes and Fixes for Cam Sensor Faults

What's Unique About the 2011-2013 Subaru FORESTER

This issue is particularly well-documented for the 2011-2013 Forester because this period saw the introduction of the new FB25 engine. Early production models were prone to this code due to incorrect sensor air gaps and sensitive ECU software logic, which was a known manufacturing issue. Subaru issued multiple Technical Service Bulletins (TSBs) to address the problem, which is unusual for a simple sensor code and points to a known design or production flaw rather than just random part failure.

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 extended cranking time
• Rough idle
• Engine stalling intermittently
• Hesitation or surging during acceleration
• Reduced fuel economy
• Engine misfires

Most Likely Causes

1. Outdated Engine Control Unit (ECU) Software 🔴 High Probability Subaru issued TSB #11-137-14 specifically to update the software logic for detecting camshaft sensor faults (P0341 and P0346), indicating the original programming was too sensitive and could set a false code.
   How to confirm: A Subaru dealership or a specialized shop with access to Subaru's software can check the current software version against the latest available file mentioned in the TSB. This is the first logical check before any hardware replacement.
   Typical fix: Reprogramming the ECU with the updated software file. This is a dealer-level repair.
   Est. part cost: $0
2. Incorrect Camshaft Position Sensor Air Gap 🔴 High Probability TSB #11-130-13R details a procedure for checking and correcting the physical clearance between the sensor and the camshaft reluctor. This was a known issue on early FB engines due to variations in the stamping of the camshaft sensor plate.
   How to confirm: Following the procedure in the TSB, a technician measures the air gap. If it is out of the specified range of 1.3 +/- 0.05mm, this is the cause. This often requires an oscilloscope to check the sensor's waveform pattern.
   Typical fix: Adding a specific shim (a thin washer) to the sensor mounting point to correct the air gap. The shim kit (part number 10130AA060 🎬 Watch: How to install shims to fix the sensor air gap.) contains shims of various thicknesses from 0.1mm to 0.8mm. This is typically a dealer-installed part.
   Est. part cost: $20-$40
3. Faulty Camshaft Position Sensor (Bank 2) 🟡 Medium Probability While less common than the TSB-related issues, the sensor itself can fail from heat and age. However, it should not be the first part replaced without ruling out the software and air gap issues.
   How to confirm: After ruling out TSBs, the easiest way is to swap the Bank 2 (driver's side) intake cam sensor with the Bank 1 (passenger's side) intake cam sensor. They are the same part. Clear the codes and drive the vehicle. If the code changes to P0341 (the Bank 1 equivalent 🎬 See this walkthrough on testing and swapping camshaft sensors.), the sensor is confirmed faulty.
   Typical fix: Replace the Bank 2 intake camshaft position sensor. The sensor is located on the front timing cover 🎬 Watch: Locate the cam and crankshaft sensors on your Forester. on the driver's side, held by a single 10mm bolt.
   Est. part cost: $40-$100
4. Damaged Wiring or Poor Connector Contact ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness and connector for the Bank 2 intake cam sensor. Check for frayed wires, corrosion in the connector pins, or a loose connection. Use a multimeter to check for proper voltage and ground at the connector.
   Typical fix: Repair the damaged wire or clean/replace the connector.
   Est. part cost: $5-$50

Rare But Worth Checking

• Timing Chain Issue: While the FB25 engine uses a timing chain designed to last the life of the engine, issues like a stretched chain or a failing tensioner can alter cam timing and trigger this code. This is a more serious mechanical issue and usually presents with other symptoms like rattling noises.
• Low or Dirty Engine Oil: The FB25 engine was known for potential oil consumption issues. Low or dirty oil can affect the operation of the AVCS (cam phasing) system, leading to camshaft timing errors that can trigger codes like P0346. Checking the oil level and condition is a critical, simple first step.
• Faulty AVCS Solenoid (Oil Control Valve): The AVCS solenoid controls oil flow to the cam phaser. If it becomes clogged or fails, it can prevent the camshaft from adjusting its timing correctly, which the cam sensor will report as a performance error. This can sometimes be diagnosed by testing the solenoid with a 12v source to see if it actuates.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0346 is the primary code present.
2. Check Engine Oil: Before any other step, check the engine oil level and condition. Low or dirty oil can cause AVCS issues and trigger this code.
3. Check for TSBs: This is the most critical step for this vehicle. Contact a Subaru dealer with the VIN to determine if TSB #11-137-14 (reprogramming) or TSB #11-130-13R (sensor shim) have been performed.
4. Inspect Wiring: Visually inspect the wiring and connector for the Bank 2 (driver's side) intake camshaft position sensor. It is located on the front timing cover. Look for any signs of damage, melting, or corrosion.
5. Swap Test: Swap the Bank 2 intake cam sensor with the Bank 1 (passenger's side) intake cam sensor. They are the same part. Clear the codes and drive the vehicle. If the code returns as P0341 (for Bank 1), the sensor you moved is faulty and needs replacement.
6. Address TSBs: If the sensor is not faulty and the TSBs have not been performed, the issue is very likely related to one of them. The vehicle may need the ECU reprogrammed or the sensor air gap checked and shimmed by a professional.
7. Advanced Diagnostics: If all the above steps fail, a more in-depth diagnosis is needed to check the AVCS solenoid, timing chain components, or a problem with the ECU itself.

Parts You'll Likely Need

• Intake Camshaft Position Sensor (Bank 2, Driver's Side) (OEM #22053AA151) — This is the sensor that generates the signal. While often not the root cause on this vehicle, it can fail and is a common replacement part for this code. The swap test is the best way to confirm failure before buying.
  Trusted brands: Subaru (OEM), Denso, NTK/NGK
  OEM price range: $80-$120
  Aftermarket price range: $40-$70
• Camshaft Position Sensor Shim Kit (OEM #10130AA060) — Required if TSB 11-130-13R is performed and the sensor's air gap is found to be out of specification. The kit contains 8 shims of varying thickness.
  Trusted brands: Subaru (OEM)
  OEM price range: $20-$40
• Camshaft Position Sensor O-Ring (OEM #13099AA050) — This is a one-time use o-ring that should be replaced whenever the camshaft position sensor is removed, per Subaru's TSBs.
  Trusted brands: Subaru (OEM)
  OEM price range: $3-$8

Related Codes That Often Appear With This One

• P0341 — Camshaft Position Sensor 'A' Circuit Range/Performance (Bank 1). If both codes appear, it could suggest a systemic issue like a timing problem, widespread wiring issue, or the ECU software glitch addressed by TSB 11-137-14.
• P0302, P0304 — Cylinder 2 or 4 Misfire. Bank 2 contains cylinders 2 and 4. An incorrect cam sensor signal can disrupt timing enough to cause misfires on that bank. TSB 11-130-13R covers both cam and misfire codes.
• P0340, P0345 — These are other camshaft sensor circuit codes. P0340 is a general Bank 1 circuit malfunction, while P0345 is a general Bank 2 circuit malfunction. Seeing them together with P0346 reinforces a timing control system problem.

Technical Service Bulletins (TSBs) & Recalls

• 11-137-14: REPROGRAMMING FILE AVAILABILITY FOR DTCS P0341 AND P0346
• 11-130-13R: DIFFICULTY STARTING, ROUGH IDLE, CAM POSITION OR MISFIRE DTCS...
• 11-100-11R: DIFFICULTY STARTING, ROUGH IDLE DTCS...

Platform-Specific Known Issues

• TSB #11-137-14: Subaru identified that the original ECU software could incorrectly trigger P0341 and P0346. The fix is a software update available at dealerships.
• TSB #11-130-13R: This bulletin, which supersedes older ones, addresses a variety of cam position codes, including P0346. It provides a detailed procedure for inspecting the sensor's air gap and adding a shim if the clearance is out of spec, a known issue on early FB engines. The torque for the sensor bolt is specified as 6.4 Nm (4.7 ft-lbs).

Mechanic-Grade Diagnostic Values

• Camshaft Position Sensor Reference Voltage — expected: ~5V. Failure: Significantly lower or no voltage indicates a problem with the ECU or wiring.
• Camshaft Position Sensor Signal Voltage (Key On, Engine Off) — expected: ~4.8V to 5V. Failure: 0V or a voltage significantly different from the reference voltage points to a faulty sensor or a short in the signal wire.
• Camshaft Position Sensor Air Gap — expected: 1.3 +/- 0.05mm (1.25mm to 1.35mm). Failure: A gap outside this range requires the installation of a specific shim to correct.
• Camshaft Position Sensor Retaining Bolt Torque — expected: 6.4 Nm (4.7 ft-lbs). Failure: Incorrect torque can lead to sensor damage or improper seating.

Scan Tool Commands That Help

• Subaru Select Monitor (SSM) or equivalent: Oscilloscope / Waveform Analysis — To visually inspect the sensor's output signal. A normal waveform should show three evenly spaced peaks followed by a longer space. An abnormal or erratic pattern, even with correct voltages, indicates a problem with the sensor, air gap, or reluctor wheel, as detailed in TSB 11-100-11R.

Wiring & Ground Locations

• ECU/ECM Ground — The main grounds for the ECU are sourced from the top of the intake manifold.. A poor ground at the intake manifold can cause a host of strange electrical issues and sensor faults, including P0346. This is especially critical if TGV deletes or phenolic spacers have been installed, as they can interrupt this ground path.
• Engine-to-Chassis Ground — A primary ground strap runs from the engine block to the chassis frame rail, often located below the battery.. This is a main ground path for the engine. If it's loose, corroded, or was not reconnected after a major repair (like a transmission or clutch replacement), it can cause sensor circuits to become unstable.
• Transmission-to-Firewall Ground — A ground strap often connects the transmission housing to the vehicle's firewall.. Similar to the main engine ground, this strap is critical and can be easily missed during transmission or clutch work. A forum user with a P0346 immediately after a CVT replacement was advised that a missed ground strap was the most likely cause.

Real Owner Repair Stories

• The Subaru Forums user 'tbearsubie' (2013 Subaru Impreza 2.0L (with same FB engine family and sensor design)) — P0346, misfires (P0300), and sometimes a no-start condition.
  ❌ Tried (didn't work) Replacing both driver's side (Bank 2) camshaft position sensors with new OEM parts.
  ✅ What actually fixed it The code appeared immediately after a non-dealer CVT replacement. The strong suspicion and recommended fix from other forum members was that a main ground strap between the engine/transmission and the chassis was not reconnected during the repair, causing the sensor circuit to malfunction.

Model Year Variations Within This Range

• 2011-2013: Early TSBs (like #11-100-11R) from 2012 noted that codes P0341 and P0346 were applicable to 2013 models only. However, later, superseding TSBs (like #11-130-13R and #11-137-14) expanded the applicability to the full 2011-2014 range. This indicates that while the issue existed across these years, the specific diagnostic parameters or factory recognition of the fault evolved, with later bulletins providing the most comprehensive repair information for all affected years.