P235B rates how well cylinder 10 burns, derived from its pressure curve – for instance from the energy each working cycle releases or from how it compares with the other nine cylinders of a V10. No manufacturer documents this code, nor the cylinder-1 equivalent P039E. CARB supplies the background: diesel passenger cars equipped with combustion or combustion quality sensors must, from model year 2010, flag misfire once it reaches 5 % of firings, counted over 1,000 revolutions – far tighter than the continuous-misfire rule other diesels long had to meet. Coked or worn injectors, partial compression loss, intake air leaks or poor fuel degrade combustion. The engine shakes, smoke and consumption rise, and the code tends to appear together with P2357 or P2358 or with the cylinder 10 misfire code P0310.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Cylinder 10 is numbered according to the manufacturer: check your engine's manual before working on it.
Symptoms
- Check engine light on
- Uneven running and vibration
- Increased smoke and fuel consumption
Most likely causes
- Coked or worn injector of cylinder 10
- Partial compression loss in cylinder 10
- Air leak in the intake tract
- Poor or contaminated fuel
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It affects emissions.
What each character of P235B means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 3: Ignition and misfires
- 5B: Specific fault in that system
Frequently asked questions
Can I keep driving with code P235B?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P235B?
The most common causes are: coked or worn injector of cylinder 10; partial compression loss in cylinder 10; air leak in the intake tract.
Related codes
- P2357Cylinder 10 Pressure Too Low
- P2358Cylinder 10 Pressure Too High
- P2353Cylinder 10 Pressure Sensor Circuit Range/Performance
- P0310Cylinder 10 Misfire Detected
- P2351Cylinder 9 Combustion Performance
- P2365Cylinder 11 Combustion Performance
- P039ECylinder 1 Combustion Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.