What it means
The idle-speed selector input is electrically intact but the value does not match a valid preset — multiple positions or a non-mappable value. Often a sticky multi-position switch.
At a glance
- Usually lights the check-engine light
How it works
The engine idle speed selector switch provides the control module with the operator's chosen idle setting, typically through a multi-position input. This range/performance code sets when the signal is present but does not correspond to a valid preset, as can happen with a contaminated rotary contact, an out-of-calibration sensor, or loose mounting.
Common causes
Most likely first.
- Contaminated rotary contact
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
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 watch the selector's live input while slowly moving it through each available position.
- Check whether the displayed input settles at a valid setting or shows multiple, unstable, or unmappable values.
- Inspect the selector switch, mounting, connector, and wiring for looseness, contamination, corrosion, or damaged terminals.
- Test switch output and circuit continuity at each position against the wiring diagram and manufacturer's specification.
- If the wiring and mounting are sound, test the selector element for wear or calibration drift before suspecting the control module.
Common fixes
- Clean or secure a contaminated or loose selector switch as permitted by the vehicle's service procedure.
- Repair poor connector contact or damaged selector wiring.
- Correct loose switch mounting that allows the signal to vary.
- Replace a worn or out-of-calibration idle speed selector.
Can I keep driving?
If the engine idles predictably, short trips are generally possible, but watch for unstable idle or stalling and avoid relying on a selected fast-idle setting. Stop in a safe place if the engine repeatedly stalls.
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.