Fuel & air metering · Powertrain · generic (SAE-defined)
P0021: "A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)
P0021 means the Bank 2 "A" camshaft, usually the intake cam on the side without cylinder 1, is more advanced than commanded or its timing control is not performing correctly.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0021 sets
The powertrain control module (PCM) sets a target angle for the Bank 2 intake cam and uses the cam and crank position sensors to confirm the cam reaches it. If the actual angle stays more advanced than desired, or the cam responds too slowly or not at all, P0021 sets. Error limits and enable conditions are manufacturer-specific.
Common causes of P0021
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Low, dirty or incorrect engine oil
- Sticking Bank 2 intake VVT oil control solenoid
- Bank 2 intake cam phaser stuck advanced
- Clogged oil screen or restricted oil passage
- Stretched timing chain on Bank 2
- Cam timing misaligned after repair
P0021 symptoms
- Check engine light on
- Rough or hunting idle
- Stalling, especially when coming to a stop
- Reduced power
- Worse fuel economy
How P0021 is diagnosed
- Check oil level, condition and viscosity
- Scan for related codes such as P0018, P0020 or P0011
- Compare desired and actual Bank 2 intake cam angle in live data
- Command the Bank 2 solenoid and watch the cam angle respond
- Inspect the solenoid and oil screen for debris
- Check timing chain stretch and phaser operation if needed
Typical fixes for P0021
- Change oil and filter with the correct specification
- Replace the Bank 2 "A" oil control solenoid
- Replace the Bank 2 intake cam phaser
- Replace worn timing chain components
- Correct cam timing
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Manufacturer notes
Commonly reported on GM V6 engines and Toyota and Lexus V6 engines with variable valve timing. Definitions can vary by manufacturer; check factory service information.
Related codes & warning lights
P0021 FAQ
What does code P0021 mean?
P0021 means the Bank 2 "A" camshaft, usually the intake cam on the side without cylinder 1, is more advanced than commanded or its timing control is not performing correctly. The standard definition is ""A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)."
Can I drive with a P0021 code?
Usually you can drive a short distance, but rough idle, stalling and sluggish acceleration are possible. Check the oil level first and have the engine diagnosed soon.
What does it mean if P0011 and P0021 are both stored?
When both banks report the same advanced condition, look first at something they share, such as oil level, oil pressure or oil quality, before replacing individual solenoids.
Can a bad oil filter cause P0021?
A wrong or restrictive filter can reduce oil flow to the phasers on some engines, so using the specified filter matters.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.