OBD-II code · Powertrain (generic)
P03AC Cylinder 3 Pressure Sensor Circuit High
Cylinder 3 pressure sensor above upper plausibility — open signal or short to B+. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P03AC?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyOpen signal line
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- Parts involved
- Cylinder Pressure Sensor
Related codes
- P0398Cylinder 1 Pressure Sensor Circuit High
- P03A2Cylinder 2 Pressure Sensor Circuit High
- P03A9Cylinder 3 Pressure Sensor Circuit
- P03B6Cylinder 4 Pressure Sensor Circuit High
- P03C0Cylinder 5 Pressure Sensor Circuit High
- P03CACylinder 6 Pressure Sensor Circuit High
- P03D4Cylinder 7 Pressure Sensor Circuit High
- P03DECylinder 8 Pressure Sensor Circuit High
- P234BCylinder 9 Pressure Sensor Circuit High
- P2355Cylinder 10 Pressure Sensor Circuit High
- P235FCylinder 11 Pressure Sensor Circuit High
- P2369Cylinder 12 Pressure Sensor Circuit High
- P03AACylinder 3 Pressure Sensor Circuit Range/Performance
- P03ABCylinder 3 Pressure Sensor Circuit Low
- P03ADCylinder 3 Pressure Sensor Circuit Intermittent/Erratic
- P03AECylinder 3 Pressure Too Low
- P03AFCylinder 3 Pressure Too High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.