What it means
A general electrical fault is reported on the engine speed input from the ignition/distributor — open, shorted, or out of plausibility. On older systems this is the distributor pickup; on newer ones it is the crank/cam-derived speed signal feeding the ignition driver.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The ignition or distributor engine-speed input provides the PCM or ignition controller with information about whether and how fast the engine is turning. This code sets when that input has a general electrical or plausibility fault, which can leave the module without a dependable speed signal.
Common causes
Most likely first.
- Engine speed or ignition pickup sensor failure
- Damaged wiring or loose connector
- Fault in the ignition or distributor signal circuit
Symptoms
- Check-engine light
- Engine may stall or fail to start
- Erratic tachometer reading
How to diagnose it
- Record freeze-frame data and check live engine RPM during cranking and running to see whether the speed input is missing or implausible.
- Inspect the ignition or distributor pickup connector and wiring for looseness, corrosion, damaged insulation, or poor routing.
- Identify the speed-input circuit from the vehicle wiring information and check its supply, ground, and signal connections as applicable to that system.
- Check the pickup or speed sensor signal during cranking using the manufacturer's test procedure, since a faulty signal can cause stalling or a no-start.
- If wiring and sensor checks pass, test the ignition or distributor signal path and the receiving module.
Common fixes
- Reconnect a loose engine-speed pickup connector and secure its wiring.
- Repair damaged or corroded wiring in the speed-input circuit.
- Replace a failed ignition or distributor pickup sensor after confirming its signal is faulty.
- Repair a confirmed fault in the ignition/distributor circuit or receiving module.
Can I keep driving?
The engine may stall or fail to start if its speed input becomes unreliable, so avoid journeys where a sudden loss of power would be hazardous. If the tachometer is erratic or the engine cuts out, have the fault addressed before continued driving.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.