P034A
Crankshaft Position Sensor - Crankshaft Start Position Incorrect
At engine start the crankshaft position reported by the sensor does not match the calibrated start window — typically a wrong tone-wheel installation, sensor air gap, or PCM not synchronised after a relearn.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Tone wheel misindexed or relearn pendingCommon
Parts involved
- Crankshaft Position Sensor
- Flywheel
P034A is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.