What it means
Engine speed input signal jumps or drops out intermittently — connector or wiring issue. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
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 sends the control module a signal that tracks engine rotation. This code sets when that signal drops out or jumps intermittently, often as a loose or damaged connection changes with vibration or harness movement.
Common causes
Most likely first.
- Intermittent connector
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check-engine light
- Intermittent stalling or hesitation
- Erratic tachometer reading
How to diagnose it
- Record freeze-frame data and monitor live RPM while the engine runs to identify whether the signal drops out when hesitation or stalling occurs.
- Inspect the pickup connector and harness for loose terminals, corrosion, water intrusion, chafing, or routing against a vibrating part.
- Wiggle the speed-input wiring and connector while monitoring RPM or signal data to locate a movement-sensitive interruption.
- Check connector terminal tension and test continuity while flexing the harness, using the vehicle wiring information.
- If the harness remains stable, test the pickup signal during operation and check the receiving circuit for an intermittent fault.
Common fixes
- Reseat a loose connector and secure its terminals.
- Repair chafed or broken wiring and reroute it away from vibration or rubbing.
- Clean or replace corroded terminals and restore connector sealing.
- Replace a pickup or speed sensor confirmed to drop out intermittently.
Can I keep driving?
Intermittent loss of the speed signal can stall the engine unexpectedly, so avoid driving in situations where a sudden stall would be hazardous. If the engine is cutting out, stop driving until the connection or sensor fault is repaired.
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.