P2651"B" Rocker Arm Actuator System Performance/Stuck Off (Bank 1)
- 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
- In the generic definition, P2651 says the B stage of rocker arm switching on bank 1 did not engage when requested, or engaged too weakly to be confirmed. Controllers usually verify the change through an oil pressure switch in the rocker gallery or through a measurable shift in engine behaviour. Honda gives the number a narrower meaning on many four-cylinder i-VTEC engines: Service Bulletin 13-021 (Accord L4 2003–12, CR-V 2002–09, Element 2003–11, Fit 2007–11, CR-Z 2011, Civic Si 2002–05 and Civic 2012–13) files P2646 or P2651 as a low-voltage fault in the rocker arm oil pressure switch circuit, may be intermittent, and the fix is a new switch. For the generic case, low or thin oil, a blocked solenoid screen and a seized locking pin are typical. P2652 is the opposite state.
- What you may notice
- MIL on, sometimes only now and then
- Engine lacks pull in the speed range served by stage B
- Fault may not return right after clearing
- Likely causes
- LikelyIntermittently failing rocker arm oil pressure switch (Honda i-VTEC)
- PossibleOil level too low or oil of the wrong grade
- PossibleClogged filter screen or sticking spool in solenoid B
- RareLocking pin in the switchable rocker arm seized by deposits
- 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: €40 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.