Powertrain, generic (extended)

P236F Cylinder 12 Combustion Performance

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

P236F is the ECM's verdict that combustion in cylinder 12 falls short, judged from the evaluated pressure curve rather than from a single limit. No manufacturer documents it, as no twelve-cylinder engine with cylinder pressure sensing is public. BorgWarner states that its pressure glow plug lets the controller correct, cylinder by cylinder, how much fuel is injected and when, with the measured pressure as feedback. A performance code of this type follows when that trimming has used up its range for one cylinder and the result is still off target. For diesels, CARB links combustion sensors to more demanding misfire monitoring. Worn or coked injectors, poor compression, a restricted intake or contaminated fuel are typical findings. Rough running, extra smoke and P0312 may appear alongside.

Likely causes

Injector of cylinder 12 coked or worn

Weak compression in cylinder 12

Contaminated or poor-quality fuel

Restricted intake path

Symptoms

Check engine light on
Rough running
More visible exhaust smoke

Repair estimate

DifficultyHardWorkshop job

Parts and labour€150–3,000

Time1–10 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

cylinder pressure sensor glow plugsensor wiringengine control modulefuel injector

References: borgwarner.com, law.cornell.edu.