P03AA Cylinder 3 pressure sensor circuit range/performance
What P03AA means
Some engines, mostly modern diesels, measure combustion pressure inside each cylinder, often with a sensor built into the glow plug. P03AA means the signal from the cylinder 3 sensor is implausible. The engine computer uses this data to fine-tune injection, so it falls back to less precise control.
P03AA is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 200–1500 €
- Workshop time
- 1–4 h
- Repair difficulty
- Hard
- DIY possible
- No
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on
- Slightly rougher running or noise
- Possible change in fuel consumption
- Often no obvious symptoms
Common causes
- Faulty pressure-sensing glow plug or cylinder pressure sensor
- Damaged wiring or corroded connector
- Carbon deposits on the sensor tip
- Injector fault on cylinder 3 affecting combustion
- Glow plug control module fault on some engines
Can I keep driving with P03AA?
You can drive, but have it checked within one or two weeks.
What to check first
- Check for glow plug or injector codes on cylinder 3
- Inspect the connector and wiring at the cylinder 3 sensor or glow plug
- Compare cylinder 3 pressure data with the other cylinders in live data
- Replace the sensor or pressure-sensing glow plug if faulty, taking care not to break it in the head
Related codes
- P0381 Glow plug/heater indicator control circuit/open
- P0380 Glow plug/heater circuit A
- P0366 Camshaft position sensor B circuit range/performance (bank 1)
- P0365 Camshaft position sensor B circuit (bank 1)
- P0363 Misfire detected, fuelling disabled
- P0356 Ignition coil F primary control circuit / open
- P0355 Ignition coil E primary control circuit / open
- P0354 Ignition coil D primary control circuit/open
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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