P0021: The intake cam on the right side is too far advanced
"A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)
Short trips only. The engine will run but performance will be off. At high RPM, over-advanced cam timing on an already worn engine can strain valve train components. Get it diagnosed soon.
What it means
The intake cam on bank 2 has moved further toward advance than the computer commanded, or it cannot return from advance. This is the bank 2 equivalent of P0011. The solenoid that controls this cam is most likely stuck open in the advance direction, often from sludge buildup. If you also have P0020 on bank 2, start with the wiring or oil. If P0021 is alone, the solenoid or phaser on bank 2 is the target.
Common causes
- Stuck VVT solenoid in the advance position on bank 2Sludge holds the solenoid open so the cam advances and cannot return to neutral.
- Dirty or old engine oilOld oil thickens and clogs the fine passages inside VVT solenoids on both banks.
- Worn bank 2 intake cam phaserA phaser that has lost internal sealing pressure drifts to advance under oil pressure.
- Timing chain stretch on bank 2On engines with separate chains per bank, one chain can stretch before the other.
What it costs
- VVT solenoid (bank 2)$80 to $250
- Cam phaser (bank 2)$500 to $1,200
- Timing chain kit$900 to $2,500
Symptoms
- Check engine light on
- Rough idle
- Stalling at idle, especially when warm
- Reduced acceleration
- Lower fuel economy
What to do next
Change the oil if it is overdue, reset the code, and test drive. If P0021 returns, replace the bank 2 intake VVT solenoid. The solenoid is the most cost-effective first step. If the code persists after a new solenoid, the phaser is likely worn and needs replacement. Check for any cold-start chain rattle before committing to a phaser job.
Lewis tracks the commanded versus actual cam advance angle on bank 2 in real time so you can confirm whether the cam is stuck or only slipping occasionally. Download Lewis.
Related codes
FAQ
- Why does my car stall at idle with P0021?
- An over-advanced intake cam on bank 2 changes the air-fuel mixture at low RPM. The engine can stall when the cam is stuck far into advance at idle speeds.
- Can I fix P0021 myself?
- The VVT solenoid swap is a reasonable DIY job on many V6 and V8 engines. The phaser or timing chain requires more skill and usually goes to a shop.
- Does P0021 affect both banks?
- No. P0021 is specific to bank 2. It only affects the cylinders on that side. Bank 1 equivalents are P0011 and P0012.