P0020: How to Diagnose & Fix — Camshaft Position 'A' Actuator Circuit (Bank 2)
3 vehicles · 3 makes · $150-$4,500 repair
How to diagnose and fix P0020: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Ford Transit · 2015–2018
The first-generation 3.5L EcoBoost (2011-2016) used in the 2015-2017 Ford Transit 350/350 HD with the twin-turbocharged V6 is known for premature timing chain stretch. The single-chain-per-bank design (two chains total) stretches as the links wear individually, causing the chain to effectively grow longer. A stretched chain causes VCT timing correlation codes, cold-start rattling, rough idle, and eventual jumped timing. Ford revised the 3.5L EcoBoost design in 2017 to use dual chains per bank (four total), which substantially resolved the stretch issue. Transit vans used for commercial/fleet service with high-idle hours accumulate chain wear faster than typical passenger vehicles. The F150 EcoBoost Forum documents thousands of cases of this specific 3.5L chain issue and contains multiple long-running troubleshooting threads.
Common Symptoms
- Cold-start rattle from engine (first 2-5 seconds on startup)
- Check engine light with P0016, P0017, P0020, P0021 (cam-crank timing correlation)
- Rough idle, especially when cold
- Poor fuel economy
- Engine hesitation or stumble
- Loss of power under acceleration
- Drivability issues that worsen over time
How to Fix
Complete timing chain replacement required: both primary chains, all guides, and tensioners must be replaced simultaneously. In 2017+, Ford redesigned to dual-chain design which resolved the issue. Remanufactured short block or long block replacement is an option for high-mileage engines if chain guides have also failed. Use only 5W-30 full synthetic and change every 5,000-7,500 miles. Labor: 10-14 hours on Transit due to engine mount complexity.
Sources for this issue (1)
Mercedes-Benz GLE · 2016–2018
The W166 GLE 350 and GLE 400 (2016-2018, M276 3.0L/3.5L V6) share the well-known M276 camshaft-adjuster problem. The variable-valve-timing camshaft adjusters and their magnets/solenoids wear, allowing the cams to fall out of time. Symptoms include a 2-3 second rattle on cold start, rough running, and check-engine codes such as P0010-style adjuster faults; owners report codes like P002177 with cams found advanced/out of time. Left unaddressed, a worn adjuster can cause poor timing control and driveability problems.
Common Symptoms
- 2-3 second rattle on cold start
- rough idle
- check engine light
- rough running / hesitation
- cam timing fault codes
How to Fix
Read the cam-correlation/adjuster DTCs and inspect the intake and exhaust camshaft adjusters and adjuster magnets. Replace worn camshaft adjusters (often with an updated timing chain kit and tensioner) and the adjuster solenoids on the affected bank, then re-verify cam timing. Using correct-spec oil and timely oil changes helps prevent adjuster sludging.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- FCP/Febi M276 bank-1 intake camshaft-adjuster repair kit 176728OEMFCP 176728
Mechanically confirmed bank-1 intake adjuster failure on the cataloged 2016-2018 GLE350 M276.955 branch Fitment/availability: The inspected direct U.S.
- OE-supplier camshaft-adjuster magnet/solenoid 2761560790OEMOE Supplier 2761560790
Electrically or leak-confirmed external adjuster magnet on the cataloged GLE350 branch Fitment/availability: The inspected direct U.S.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (2)
Subaru WRX STI · 2004–2021
The Active Valve Control System (AVCS) solenoids on the EJ257 engine are prone to failure from oil contamination and carbon buildup. When they stick or fail, the ECU cannot properly adjust camshaft timing, causing rough idle, hesitation, and reduced power. The solenoids are oil-controlled and degrade faster with extended oil change intervals or contaminated oil.
Common Symptoms
- Check engine light with AVCS-related codes
- Rough or hunting idle
- Hesitation on acceleration
- Reduced power in mid-range RPMs
- Occasional stalling at idle
How to Fix
Replace the failed AVCS solenoid(s) — there are two on the EJ257, one per bank ($80-$150 each for parts). Clean the oil passages feeding the solenoids during replacement. Use OEM Subaru solenoids for reliability. Prevent future failures by using quality synthetic oil and changing every 3,000-4,000 miles under hard driving conditions. Some owners clean solenoids with brake cleaner as a temporary fix.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Subaru 10921AA020 Intake AVCS Oil Control Valve
early intake OCV only after that valve fails electrical/hydraulic response testing Fitment/availability: EJ257 model years 2004-2006 intake AVCS position; sold individually, confirm VIN and bank Fitment/availability: In stock and ready t…
- Genuine Subaru 10921AA080 Intake AVCS Oil Control Valve
middle intake OCV branch only after that valve fails electrical/hydraulic response testing Fitment/availability: EJ257 model years 2006-2010 intake AVCS position; overlap years require VIN confirmation, sold individually Fitment/availabi…
- Genuine Subaru 10921AA140 Intake AVCS Oil Control Valve
late intake OCV branch only after that valve fails electrical/hydraulic response testing Fitment/availability: EJ257 model years 2010-2021 intake AVCS position; overlap years require VIN confirmation, sold individually Fitment/availabili…
- Genuine Subaru 10917AA060 Right Exhaust AVCS Oil Control Valve and Holder
right exhaust valve/holder assembly only after right exhaust response or contamination failure is proven Fitment/availability: EJ257 model years 2008-2021 right-hand exhaust AVCS position only; confirm VIN Fitment/availability: In stock …
- Genuine Subaru 10917AA070 Left Exhaust AVCS Oil Control Valve and Holder
left exhaust valve/holder assembly only after left exhaust response or contamination failure is proven Fitment/availability: EJ257 model years 2008-2021 left-hand exhaust AVCS position only; confirm VIN Fitment/availability: In stock and…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipClean your AVCS solenoids every 30,000 miles as preventive maintenance. Remove them, spray with brake cleaner, and reinstall. Takes 20 minutes per side.
- TipShort oil change intervals (3,000-4,000 miles) with quality synthetic oil are the best prevention. The EJ257 is hard on oil and dirty oil kills AVCS solenoids.
Find P0020 by make
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P0020 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0020 mean?
P0020 stands for "Camshaft Position 'A' Actuator Circuit (Bank 2)." P0020 is a generic powertrain code indicating a fault in the camshaft position (intake/'A') actuator circuit on bank 2 — the side of the engine that does not contain cylinder number one. The engine computer controls a variable valve timing (VVT) solenoid to advance or retard camshaft timing for efficiency and power; this code sets when it detects an electrical problem in that solenoid's control circuit. The result can be reduced performance, rough running, or poor fuel economy. It is usually not an immediate breakdown risk but should be diagnosed to prevent driveability and timing issues.
What are the most common causes of P0020?
The most common causes of P0020 are: Faulty bank 2 camshaft (VVT/oil control) solenoid, Wiring or connector damage to the VVT solenoid, Low or dirty engine oil restricting VVT operation, Clogged VVT solenoid screen/oil passage, Open or short in the actuator control circuit, Failed PCM/ECM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0020?
Repair costs for P0020 range from $150 to $4,500, depending on the vehicle and root cause.
Which vehicles are affected by P0020?
Au7o has documented P0020 across 3 vehicle models from 3 manufacturers: Ford, Mercedes-Benz, Subaru.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.