P0018 on 2020-2022 Subaru Outback: Crank/Cam Correlation Causes and Fixes

What's Unique About the 2020-2022 Subaru OUTBACK

For this specific generation of Subaru Outback with the 2.5L FB25D engine, the most significant factor for a P0018 code is a known software issue. Subaru issued Technical Service Bulletin #09-120-24R, acknowledging that the ECM's diagnostic logic could be overly sensitive and trigger this code, along with P0016, P0017, and P0019, incorrectly. This means that unlike on many other vehicles where this code immediately points to a mechanical or sensor failure, the first and most crucial step for a 2020-2022 Outback is to check if a simple dealer-installed software update is needed. This can save owners significant time and money by avoiding unnecessary hardware replacements.

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
• Multiple warning lights illuminated on the dashboard (e.g., Traction Control, EyeSight disabled) as a secondary effect of the engine fault.
• Rough or unstable idle
• Engine hesitation or stalling, particularly under load.
• Reduced engine power and acceleration
• Decreased fuel economy
• Rattling or ticking noise from the engine, which in some cases has disappeared after replacing a faulty OCV.

Most Likely Causes

1. Outdated Engine Control Module (ECM) Software 🔴 High Probability → Shop Engine Control Module (ECM) Subaru released TSB #09-120-24R specifically for this issue on 2020-2022 Outbacks, indicating the original diagnostic logic was too sensitive and required enhanced logic to prevent false codes.
   How to confirm: A Subaru dealer or a shop with a Subaru Select Monitor (SSM) or access to the service database can check your vehicle's VIN to see if the update has been performed.
   Typical fix: Reprogramming the ECM with the updated file provided by Subaru. This is a dealer-level or specialized shop repair.
   Est. part cost: $0
2. Low or Dirty Engine Oil 🟡 Medium Probability The AVCS system is hydraulic and relies on clean oil at the correct pressure to function. The FB25 engine has small oil passages that are sensitive to sludge or low oil levels, which can cause the camshaft phasers to respond slowly and trigger a correlation error.
   How to confirm: Check the oil level on the dipstick and inspect its condition. If it's low, dark, or appears sludgy, it is a likely contributor. An oil flush may be recommended by some mechanics.
   Typical fix: Perform an oil and filter change using the manufacturer-specified 0W-20 oil. Clear codes and perform a drive cycle to see if the fault returns.
   Est. part cost: $50-$100
3. Faulty Oil Control Valve (OCV) / VVT Solenoid 🟡 Medium Probability → Shop Engine Variable Valve Timing (VVT) Solenoid The OCV for Bank 2 (driver's side intake, top position) can become clogged with sludge or fail electronically, preventing it from directing oil to the cam phaser correctly. This is a very common failure point across many Subaru models.
   How to confirm: A mechanic can test the solenoid's operation with a scan tool or by applying direct power. A common DIY method is to swap the Bank 2 intake OCV with the Bank 1 intake OCV; if the code changes to P0016, the OCV is faulty. The resistance across the terminals should be between 6-12 ohms.
   Typical fix: Replace the Bank 2 intake Oil Control Valve. 🎬 Watch: See how to replace and upgrade the oil control valve. One owner on a forum noted a persistent ticking noise at idle went away after replacing the OCV.
   Est. part cost: $70-$150
4. Faulty Camshaft Position Sensor ⚪ Low Probability → Shop Engine Camshaft Position Sensor
   How to confirm: Swap the Bank 2 intake cam sensor with the Bank 1 intake sensor. If the code changes to P0016, the sensor is bad. A multimeter can also be used to test the sensor's output.
   Typical fix: Replace the faulty camshaft position sensor. One user on a Reddit forum replaced both the OCV and sensor to resolve the issue.
   Est. part cost: $40-$120

Rare But Worth Checking

• Stretched Timing Chain: → Shop Engine Timing Chain While less common on newer vehicles, significant mileage or poor maintenance can lead to chain stretch, causing a permanent timing correlation error. This is a major mechanical repair often costing thousands of dollars.
• Damaged Camshaft Phaser / AVCS Sprocket: → Shop Engine Camshaft The actuator sprocket on the end of the camshaft can fail mechanically, getting stuck in one position. This usually requires timing component replacement and can be a very expensive repair.
• Clogged Oil Passages or OCV Filter Screens: Sludge or debris from infrequent oil changes can clog the small filter screens on the OCVs or the oil passages leading to the cam phasers. In some cases, an engine oil flush is recommended to clear these passages.

Diagnosis Steps

1. Verify the code with an OBD-II scanner.
2. CRITICAL FIRST STEP: Contact a Subaru dealer and reference TSB #09-120-24R. Ask if your vehicle's VIN is covered and if the ECM has the latest software update to correct false P0018 codes.
3. Check the engine oil level and condition. If low or dirty, perform an oil and filter change with 0W-20 synthetic oil, clear the code, and perform a drive cycle to see if it returns.
4. Using a scan tool, monitor live data for the crankshaft and camshaft position sensors. Look for any erratic readings or dropouts.
5. Inspect the wiring and connectors for the Bank 2 (driver's side) intake camshaft position sensor and the oil control valve for any damage or corrosion.
6. Test the Bank 2 intake Oil Control Valve (OCV). The easiest test is to swap it with the Bank 1 (passenger's side) intake OCV. Clear the codes and drive the vehicle. If the code changes to P0016, the OCV is confirmed to be faulty. Alternatively, check the resistance between the two terminals of the OCV; it should be between 6 and 12 ohms.
7. If the OCV swap does not move the code, perform the same swap test with the camshaft position sensors between Bank 1 and Bank 2 to rule out a faulty sensor.
8. If all previous steps fail, a mechanical inspection of the timing chain, tensioners, and guides is necessary to check for stretching or damage. This is a labor-intensive job best left to a professional.

Parts You'll Likely Need

• Engine Control Module (ECM) Reprogramming — Subaru has identified that the original software logic can falsely trigger P0018, making a software update the most likely required fix per TSB 09-120-24R.
  Trusted brands: Subaru (Dealer Service)
  OEM price range: $100-$200
  Aftermarket price range: N/A
• Oil Control Valve (VVT Solenoid) (OEM #10921AA231) — This valve controls oil flow to the cam phaser and is a common failure point if it becomes clogged or fails electronically. It is used for both intake and exhaust positions on many FB/FA engines.
  Trusted brands: Subaru (OEM), Denso, Dorman
  OEM price range: $90-$150
  Aftermarket price range: $70-$120
• Camshaft Position Sensor (OEM #22056AA28A) — If the sensor itself fails, it will send incorrect data to the ECM, causing the correlation code. This is less common than the OCV or software issue. Part number is for the 2.5L engine in this vehicle but should be verified with VIN.
  Trusted brands: Subaru (OEM), Denso, NTK
  OEM price range: $25-$40
  Aftermarket price range: $20-$35

Related Codes That Often Appear With This One

• P0016 — This is the same correlation error but for Bank 1 (passenger side). Seeing both P0018 and P0016 together often points to a systemic issue like low oil, a faulty crankshaft sensor, or a stretched timing chain. Both are also addressed by TSB 09-120-24R.
• P0019 — This is a correlation error for the exhaust camshaft on the same bank (Bank 2). If seen with P0018, it suggests a broader timing or oiling problem on the driver's side of the engine. This code is also addressed by the same software update TSB.
• P0017 — This is the correlation error for the exhaust camshaft on Bank 1. Seeing all four codes (P0016, P0017, P0018, P0019) is a strong indicator of a base timing issue (e.g., timing chain) or a systemic problem like severe oil sludge. All four are mentioned in TSB 09-120-24R.

Technical Service Bulletins (TSBs) & Recalls

• 09-120-24R: Announces new ECM reprogramming files to remedy false P0016, P0017, P0018, and P0019 codes due to overly sensitive diagnostic logic. Applies to 2020-22 Legacy/Outback 2.5L, as well as Forester, Impreza, and Crosstrek models.
• 09-120-24: The original version of the bulletin announcing the ECM reprogramming files.
• 02-163-16R: An older, general TSB providing detailed inspection procedures for AVCS-related DTCs on various FA and FB engines, which can be a useful reference for diagnostic steps beyond the software update.

Platform-Specific Known Issues

• A primary issue for the 2020-2022 Outback 2.5L is the ECM's sensitivity, which can cause it to store DTCs P0016, P0017, P0018, or P0019 incorrectly. Subaru released updated software (TSB 09-120-24R) to fix this.
• Owners on forums frequently report that the first step should always be checking for the software update, as many have needlessly replaced parts only for the code to return.

Mechanic-Grade Diagnostic Values

• Engine Oil Pressure at Idle (Warm Engine) — expected: > 10 PSI. Failure: Pressure below 10 PSI indicates an oiling problem that will prevent the AVCS system from working correctly.
• Engine Oil Pressure at 3,000 RPM (Warm Engine) — expected: > 30 PSI. Failure: Pressure below 30 PSI under load points to a significant oil supply issue.
• Oil Control Valve (OCV) / VVT Solenoid Resistance — expected: 6 to 12 ohms. Failure: A reading outside this range indicates an electrical failure in the solenoid coil.
• VVT Advance Angle Amount at Idle (OCV disconnected) — expected: ±10 degrees from 0. Failure: A value greater than ±10 degrees from 0 with the OCV disconnected suggests a mechanical timing issue (e.g., jumped tooth), as the cam should be at its base position.

Hidden / Shadow Codes Worth Checking

• Mode $06, Monitor ID $36, TID $8B/$8C/$8D/$8E: This refers to non-continuous monitor test results for the AVCS system stored in the ECM. A diagnostic value greater than 1000 can indicate a failure, even before a standard DTC is set. This is an advanced way to verify if a problem exists after a repair. (see via Requires a Subaru Select Monitor (SSM) or an advanced scan tool capable of reading OBD Mode $06 data.)

Scan Tool Commands That Help

• Subaru Select Monitor (SSM): VVT Adv. Ang. Amount (Live Data) — Used to check the camshaft's actual advance angle in real-time. This is critical for diagnosing if the cam is stuck, not responding, or if the base mechanical timing is off.
• Subaru Select Monitor (SSM): Clear Memory — Used to reset stored error codes and learned values after a repair. For some AVCS issues, clearing the ECM's learned corrections is a necessary step.
• Subaru Select Monitor (SSM) or equivalent: Active Test / Bidirectional Control for OCV — Allows a technician to manually command the Oil Control Valve on and off to verify its mechanical and electrical operation without removing it from the engine.

Wiring & Ground Locations

• GE-1 / Engine Ground — On top of the engine, often near the throttle body or intake manifold. There are typically two 12mm bolts securing ground wires for the main engine loom.. A loose or corroded main engine ground can cause erratic sensor readings and bizarre electronic behavior, including nonsensical error codes. One owner of a 2021 Outback reported a loose 'GE-1' ground bolt caused widespread electronic havoc that baffled technicians until it was discovered and tightened.
• Data Link Connector — In the lower portion of the instrument panel on the driver's side.. This is the port used to connect the OBD-II scanner or Subaru Select Monitor to communicate with the ECM for diagnosis, software updates, and clearing codes.

Real Owner Repair Stories

• Reddit user Prestigious_Panic373 (Subaru WRX (similar FA/FB engine architecture)) — P0018 code appeared with no change in drivability. A ticking noise was heard at idle for about a year.
  ❌ Tried (didn't work) Initially, just clearing the code.
  ✅ What actually fixed it The user first replaced the oil control solenoid (OCV), which immediately eliminated the year-long ticking noise. The code returned, so they then replaced the camshaft position sensor. After this, the code was still present as a 'permanent' code. It took several drive cycles for the permanent code to clear on its own, after which the issue was resolved. The final fix was a combination of replacing the OCV and cam sensor, followed by performing the required drive cycles.
• Reddit user murf_9x (Subaru (model not specified, but P0018 issue)) — P0018 code along with multiple other warning lights, which were determined to be side effects of the primary engine code.
  ❌ Tried (didn't work) Online diagnosis based on codes alone.
  ✅ What actually fixed it A shop diagnosed the issue as a timing chain problem requiring replacement. The shop also stated that a new ECM would be required, estimating the total repair at $3800. This represents a worst-case scenario where the issue is purely mechanical.
• Reddit user New_Specialist_5205 (Subaru Crosstrek (FB engine)) — P0018 code with Check Engine, Traction Control, and other warning lights on.
  ❌ Tried (didn't work) Considering a full timing job.
  ✅ What actually fixed it Another user in the thread confirmed they had the same code and fixed it by replacing the VVT solenoid (OCV). The original poster decided to try this cheaper fix first.

OEM Part Supersession History

• 10921AA220, 10921AA230 → 10921AA231 — Part revision and improvement by the manufacturer.
  Heads up: The newer part number 10921AA231 is the correct replacement for the older versions and should be used for repairs.