The MAF signal voltage/frequency is too low. On the 987 this is a dirty/failed MAF, an air-intake restriction, or a wiring problem. Low MAF causes under-fuelling and lean codes.
SYMPTOMS
- Check-engine light
- Rough idle
- Hesitation
- Power loss
LIKELY CAUSES
- Dirty or failed MAF element
- Open or short in MAF wiring
- Intake blockage / clogged filter
- Connector fault
DIAGNOSIS STEPS
- Check MAF wiring and connector
- Inspect and clean the sensor element
- Verify the MAF reading at idle
- Replace the MAF if unresponsive
RELATED PARTS
- MAF sensor
- Wiring