P236BCylinder 12 Pressure Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P236B reports that cylinder 12 builds too little combustion pressure while its sensor circuit itself is in order. No manufacturer documents the code, because no V12 or W12 with cylinder pressure measurement has been made public. A weak peak means this cylinder lacks air, fuel or sealing: a valve that does not close fully, a worn ring pack, a head gasket leaking towards a neighbour, or an injector delivering too little. Where cylinders are numbered bank by bank, 12 shares its bank with 7 to 11, so a compression test across that whole bank is worthwhile. A gas leak past the sealing element of the pressure glow plug also lowers the value. Rough idle and the misfire code P0312 often come with it; P236C is the deviation in the other direction.
- What you may notice
- Check engine light on
- Rough idle and vibration
- Misfire code for cylinder 12 stored as well
- Likely causes
- PossibleIntake or exhaust valve of cylinder 12 not sealing
- PossibleWorn piston rings or head gasket leak
- PossibleInjector delivering too little fuel
- RareGas leaking past the glow plug seal
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €3,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.