What it means
Idle-speed selector input reads stuck low — short to ground or analog signal at minimum. 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
How it works
The engine idle speed selector switch supplies an input the control module uses to choose an idle setting. This circuit-low code sets when the selector signal is held below its expected range, commonly because the signal wire is shorted to ground or a connector has a poor contact.
Common causes
Most likely first.
- Switch wire shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
How to diagnose it
- Save freeze-frame data and monitor the selector input live to confirm that it stays at the low end while the switch is moved.
- Inspect the selector connector and harness for chafing, water intrusion, corrosion, or a pushed-back pin that could pull the signal low.
- With the circuit identified from the wiring diagram, check the signal wire for an unintended short to ground.
- Check connector contact and the selector's supply and ground, where fitted, against the manufacturer's specification.
- If the harness tests correctly, test the selector switch output before considering a control-module fault.
Common fixes
- Repair a selector signal wire shorted to ground.
- Replace or repair chafed harness insulation and secure the harness away from rubbing points.
- Clean or replace corroded or poorly seated connector terminals.
- Replace the selector switch if its output remains low despite a sound circuit.
Can I keep driving?
If idle remains stable, a short drive may be possible, but avoid relying on a chosen idle setting and watch for stalling, especially at stops or after a cold start. Stop driving if the engine repeatedly stalls or cannot maintain a safe idle.
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.