P0321: Ignition/Distributor Engine Speed Input Circuit Range/Performance
Do not keep driving
Expect rough running, stalling or erratic timing. Ask for the distributor shaft to be checked for play, not just the electrical signal.
What this code means
The engine speed signal is present but implausible — erratic, or disagreeing with other speed references the module holds. Mechanical wear is a real cause here in a way it is not for solid-state sensors: a distributor shaft with worn bearings lets the pickup gap wander as the engine runs, producing a signal that is unstable without any electrical fault.
Likely causes
Start here
- Worn distributor shaft or bearings · moderate
- Faulty ignition module or pickup · moderate
- Incorrect pickup air gap · moderate
Less common
- Intermittent wiring fault · moderate
- Electrical interference from ignition leads · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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- The car — make, model, year and engine. The same fault behaves differently on each.
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