OBD-II code · Powertrain (generic)
P050B Cold Start Ignition Timing Performance
During cold-start the ECU retards ignition timing to raise exhaust temperature for catalyst light-off. The strategy does not deliver the expected timing - feedback from knock sensor or combustion model shows ignition too far advanced or retarded for the demanded calibration.
Is it safe to drive with P050B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyKnock sensor drift causes wrong feedback
- PossibleCam phaser offset against crank
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–3 h
- Emissions test
- Likely to fail
- Parts involved
- Ignition Timing Strategy, Knock Sensor, Cam Position Sensor
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.