P03C3 code meaning
Cylinder 5 Pressure Too High
Powertrain system Generic code P03xx codes Check engine light
What P03C3 means
Some diesels have a combustion pressure sensor in the glow plug; the engine module uses it to control injection for each cylinder. This code concerns cylinder 5. P03C3 means the pressure measured or calculated for the cylinder is higher than expected. The 'pressure too high' codes are documented only at Audi, for cylinders 1 to 4 of the 2015 S3 gasoline engine, where a software fault mis-detected misfire. On diesels with pressure-sensing glow plugs GM patents describe a peak pressure above its limit – too much or too early injection, or a sensor drifting upwards. For cylinder 5, which only engines with at least 5 cylinders have, no manufacturer document available to us uses the code; the description follows that logic and CARB. If the cylinder is shut off, power drops noticeably.
P03C3 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P03C3
- EPC or check engine light on
- Misfire codes, possibly a cylinder shut off with noticeable loss of power
- Rough running
Common causes of P03C3
- PossibleInjector delivering too much or dripping
- PossibleSensor drifting upwards (diesel pressure-sensing glow plug)
- Less likelyKnock or pre-ignition on a gasoline engine
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 P03C3 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3 | Area: ignition system or misfire. |
| C3 | The exact fault in that area. |
What to do next
- Note P03C3 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 P03C3
What does P03C3 mean?
P03C3 means "Cylinder 5 Pressure Too High". Some diesels have a combustion pressure sensor in the glow plug; the engine module uses it to control injection for each cylinder. It is a generic code, so it means the same on every make.
Is it safe to drive with P03C3?
Drive gently and only to a workshop. With P03C3 the car can go into limp mode (reduced power) to protect itself.
Will P03C3 fail an emissions test?
Yes, it can. P03C3 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 P03C3 to fix?
Difficulty: medium. A typical repair takes 0.5 to 4 hours of work. This is a job for a workshop.
Will P03C3 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.