What it means
No engine speed signal from the ignition/distributor — open circuit, dead pickup, or sensor air gap too wide.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The ignition or distributor engine-speed input tells the control module that the engine is turning. This code sets when the module receives no speed signal, which can prevent it from controlling ignition correctly and may trigger reduced-power operation.
Common causes
Most likely first.
- Failed engine speed or ignition pickup sensor
- Damaged wiring or loose connector
- Excessive sensor air gap
Symptoms
- Check-engine light
- Engine may stall or fail to start
- Tachometer may not register engine speed
How to diagnose it
- Record freeze-frame data and watch live RPM while cranking; a zero reading when the engine is turning supports a missing speed signal.
- Inspect the engine-speed sensor or distributor pickup connector and wiring for disconnection, damage, corrosion, or a loose ground or supply connection.
- Check the sensor mounting and air gap against the manufacturer's specification, since excessive clearance can prevent a usable signal.
- Test for the sensor output during cranking using the vehicle's wiring information and the manufacturer's procedure.
- If the sensor produces a signal, trace it through the harness to the receiving module and check for an open or poor connection.
Common fixes
- Reconnect a loose or disconnected speed-sensor or pickup plug.
- Repair damaged wiring or poor connector contacts in the speed-input circuit.
- Correct a sensor mounting or air-gap problem to the manufacturer's specification.
- Replace the pickup or speed sensor if it fails the signal test.
Can I keep driving?
A missing engine-speed signal can cause stalling, a no-start, or reduced power; avoid driving if the engine cuts out or enters reduced-power operation. If it will not start reliably, arrange repair before using the vehicle.
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.