Insufficient EGR flow detected. Note: many naturally-aspirated 987 flat-sixes do not use EGR; applicability is engine-specific.
SYMPTOMS
- Check-engine light
- Possible knock under load
- Mild emissions effect
LIKELY CAUSES
- Clogged EGR passages
- Stuck EGR valve
- Faulty EGR sensor
- Vacuum/control fault
DIAGNOSIS STEPS
- Verify the vehicle has EGR
- Inspect EGR valve and passages
- Test EGR operation in live data
RELATED PARTS
- EGR valve