P03AD code meaning
Cylinder 3 Pressure Sensor Circuit Intermittent/Erratic
Powertrain system Generic code P03xx codes Check engine light
What P03AD 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 3. P03AD means the sensor signal is erratic or drops out for moments. GM's European 2.0 CDTI diesel (Saab 9-5, 2010) calls it 'circuit erratic' and sets it when the signal is outside its range for more than 0.2 s with the engine running; its fault table groups the erratic and pressure variation codes together as signal performance faults. The test plan checks a reference of 4.8–5.2 V and a ground below 5 Ω before the glow plug is replaced. Typical causes are a loose contact at the glow plug connector, a chafed engine harness or sensor electronics that become unstable with temperature. The code often comes and goes; combustion control for the cylinder is suspended while it is active.
P03AD at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P03AD
- Check engine light on
- Occasionally rough running
- Often no symptoms, the code comes and goes
Common causes of P03AD
- Most likelyLoose contact at the glow plug connector
- PossibleChafing or broken wire in the engine harness
- PossibleSensor electronics of the glow plug unstable with temperature
- Less likelyInterference from ground problems
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 module
What each part of P03AD 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. |
| AD | The exact fault in that area. |
What to do next
- Note P03AD 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 P03AD
What does P03AD mean?
P03AD means "Cylinder 3 Pressure Sensor Circuit Intermittent/Erratic". 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 P03AD?
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 P03AD fail an emissions test?
Yes, it can. P03AD 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 P03AD to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P03AD 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.