P0321
Ignition/Distributor Engine Speed Input Circuit Range/Performance
Engine speed input from the ignition/distributor is in electrical range but plausibility check fails — slow response, drift, or noise.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Sensor drift or pickup gap wrongCommon
- Sensor element aged beyond calibration windowLess likely
- Sensor mounting loose - signal dampingLess likely
Parts involved
- Ignition Distributor
P0321 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.