OBD-II code · Powertrain (generic)
P03B5 Cylinder 4 Pressure Sensor Circuit Low
Cylinder 4 pressure sensor below lower plausibility — short to ground. 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 P03B5?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyShort to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
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
- P0397Cylinder 1 Pressure Sensor Circuit Low
- P03A1Cylinder 2 Pressure Sensor Circuit Low
- P03ABCylinder 3 Pressure Sensor Circuit Low
- P03B3Cylinder 4 Pressure Sensor Circuit
- P03BFCylinder 5 Pressure Sensor Circuit Low
- P03C9Cylinder 6 Pressure Sensor Circuit Low
- P03D3Cylinder 7 Pressure Sensor Circuit Low
- P03DDCylinder 8 Pressure Sensor Circuit Low
- P234ACylinder 9 Pressure Sensor Circuit Low
- P2354Cylinder 10 Pressure Sensor Circuit Low
- P235ECylinder 11 Pressure Sensor Circuit Low
- P2368Cylinder 12 Pressure Sensor Circuit Low
- P03B2Cylinder 3 Combustion Performance
- P03B4Cylinder 4 Pressure Sensor Circuit Range/Performance
- P03B6Cylinder 4 Pressure Sensor Circuit High
- P03B7Cylinder 4 Pressure Sensor Circuit Intermittent/Erratic
- P03B8Cylinder 4 Pressure Too Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.