P231ECylinder 11 Air-Fuel Ratio Imbalance - Adjustment At Limit During Balance
- 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
- P231E belongs to cylinder 11 and can only come from twelve-cylinder engines, V12 or W12. The per-cylinder fuel trim for cylinder 11 sits at its limit during balancing. There is no public manufacturer description and no NHTSA bulletin. On such engines six cylinders share each bank, so one deviating cylinder shifts the bank sensor signal only slightly; that is one reason CARB accepts a bank or misfire code where a single cylinder cannot be resolved. Mercedes' M177 bulletin for the cylinder 7 code of the same series shows that a software update can be the real remedy. In the workshop, compare the trim values and misfire counts of cylinder 11 (P0311, P21A6) with its neighbours before the injector is replaced.
- What you may notice
- Check engine light on
- Rough idle, possibly misfire on cylinder 11
- Higher fuel consumption or exhaust smell
- Likely causes
- LikelyInjector of cylinder 11 delivering too much or too little (deposits, wear)
- PossibleAir leak at the intake port or injector seal of cylinder 11
- PossibleValve of cylinder 11 not sealing (worn seat or guide), low compression
- RarePoor contact at the connector of injector 11
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.