OBD-II code · Powertrain (generic)
P03BA Cylinder 4 Pressure Variation Low
Cylinder-to-cylinder pressure variation on cylinder 4 is below the calibrated minimum — pressure stays unusually constant cycle-to-cycle, often a sign that the closed-loop combustion controller has lost authority or the sensor signal is filtered.
Is it safe to drive with P03BA?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelySensor signal filtered
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Likely to fail
- Parts involved
- Cylinder Pressure Sensor
Related codes
- P039CCylinder 1 Pressure Variation Low
- P03A6Cylinder 2 Pressure Variation Low
- P03B0Cylinder 3 Pressure Variation Low
- P03B3Cylinder 4 Pressure Sensor Circuit
- P03C4Cylinder 5 Pressure Variation Low
- P03CECylinder 6 Pressure Variation Low
- P03D8Cylinder 7 Pressure Variation Low
- P03E2Cylinder 8 Pressure Variation Low
- P234FCylinder 9 Pressure Variation Low
- P236DCylinder 12 Pressure Variation Low
- P03B7Cylinder 4 Pressure Sensor Circuit Intermittent/Erratic
- P03B8Cylinder 4 Pressure Too Low
- P03B9Cylinder 4 Pressure Too High
- P03BBCylinder 4 Pressure Variation High
- P03BCCylinder 4 Combustion Performance
- P03BDCylinder 5 Pressure Sensor Circuit
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.