Fault in idle speed control. On the drive-by-wire 987 idle is managed by the electronic throttle.
SYMPTOMS
- Check-engine light
- Unstable idle
- Stalling
- High or low idle
LIKELY CAUSES
- Dirty or faulty throttle body
- Vacuum leak
- Wiring fault
DIAGNOSIS STEPS
- Inspect/clean the throttle body
- Smoke-test the intake
- Check throttle adaptation in live data
RELATED PARTS
- Throttle body (drive-by-wire)