P0315Crankshaft Position System Variation Not Learned
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Manufacturing tolerances of the crankshaft tone wheel distort the speed fluctuations misfire detection relies on, so the engine module learns a correction for each tooth or segment. P0315 means these values have not been learned or are invalid. GM checks that the learned tooth angles add up to 360° (deviation above 0.001° sets the code in the first trip) and learns them with a scan tool: brakes held, full throttle in park until fuel cut-off. Ford learns the profile during up to three overrun phases from 60 to 40 mph and sets P0315 when that fails. Until relearned, misfire detection is suspended – at GM above 1,000 rpm – and misfire readiness stays incomplete. The relearn is needed after replacing the engine, engine module, crankshaft, damper or crankshaft sensor.
- What you may notice
- Check engine light on (GM; Ford depending on application)
- Driving usually unaffected
- Misfire readiness not set – emissions test fails
- Likely causes
- LikelyRelearn not performed after replacing sensor, crankshaft, damper, engine or engine module
- PossibleLearned values lost through voltage loss (battery disconnected)
- PossibleTone wheel damaged or shifted, crankshaft runout, dirt on the sensor
- RareInterference in the crankshaft sensor circuit
- RareEngine module memory faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.