P2657"A" Rocker Arm Actuator System Stuck On (Bank 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2657 is the stuck-on case for bank 2: actuator A keeps the rocker arms of the second bank in their switched mode after the controller has asked for the base setting. On a cylinder deactivation design that could mean valves stay closed on that side; on a two-step design the high-lift profile stays active at idle. No manufacturer documents P2657 publicly; GM's bank 1 test P2647 (2015, 15OBDG05) shows the principle, flagging a pressure ripple below its limit during a deliberate toggle. A solenoid that leaks oil when off, a jammed locking pin or debris in the oil passage of that bank are candidates. Misfires on one bank and a lumpy idle are typical.
- What you may notice
- Misfire codes on bank 2 cylinders
- Lumpy idle
- Poor low-speed driveability
- Likely causes
- LikelyBank 2 solenoid passing oil while switched off
- PossibleLocking pin stuck in the engaged position
- RareDebris in the bank 2 oil passage
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.