P0566 Cruise Control Off Signal Malfunction

P0566 indicates a cruise control off signal malfunction. The controller sees an invalid, missing, or stuck cruise off input.

Code details

Generic OBD-II · P0

System: Speed / Idle
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace cruise actuators until the off and cancel inputs are verified.

Symptoms of P0566

Unstable, high, or low idle, or stalling.
Erratic speedometer, cruise-control, or shift behaviour.
Check-engine light with a hesitation or surge.

Common causes of P0566

A dirty throttle body, idle-control valve, or throttle-position sensor.
A failing vehicle-speed or wheel-speed sensor, or its wiring.
Vacuum leaks or a related sensor forcing the idle/speed strategy.

Useful checks before replacing parts

Compare cruise off switch state, on switch state, cancel inputs, brake switch data, steering wheel control data, and freeze-frame conditions.
Inspect switch contacts, clockspring wiring, steering column connectors, shared resistor circuits, water intrusion, and module communication faults.
Operate off and cancel controls while monitoring live data to verify input changes are clean and not stuck.

Related OBD-II codes

These nearby speed / idle entries can help compare wording and pin down the fault area.