P235B code meaning
Cylinder 10 Combustion Performance
Powertrain system Generic code P23xx codes Check engine light
What P235B means
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.
P235B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor1 to 9 hours
- Clears after repairAfter a drive cycle
Symptoms of P235B
- Check engine light on
- Uneven running and vibration
- Increased smoke and fuel consumption
Common causes of P235B
- Most likelyCoked or worn injector of cylinder 10
- PossiblePartial compression loss in cylinder 10
- Less likelyAir leak in the intake tract
- Less likelyPoor or contaminated fuel
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Cylinder pressure sensor glow plugSensor wiringEngine control moduleFuel injector
What each part of P235B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 5B | The exact fault in that area. |
What to do next
- Note P235B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P235B
What does P235B mean?
P235B means "Cylinder 10 Combustion Performance". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P235B?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P235B fail an emissions test?
Yes, it can. P235B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P235B to fix?
Difficulty: hard. A typical repair takes 1 to 9 hours of work. This is a job for a workshop.
Will P235B clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.