The DME detected misfires across multiple or random cylinders. On the flat-six, coil packs and spark plugs are the most common cause; a shared cause (vacuum leak, low fuel pressure, secondary-air/intake fault) often produces random rather than single-cylinder misfires. A flashing CEL means active catalyst-damaging misfire - stop driving.
SYMPTOMS
- Rough idle
- Check-engine light (may flash)
- Loss of power / hesitation
- Stumble under load
LIKELY CAUSES
- Worn spark plugs or failing ignition coils (multiple)
- Vacuum/intake leak (AOS, boots)
- Low or high fuel pressure (DFI HPFP on 987.2)
- Dirty MAF or lean mixture
- Weak battery/charging causing coil dropout
DIAGNOSIS STEPS
- Read freeze-frame and per-cylinder misfire counters
- Inspect plugs and coils; replace as a set if aged
- Smoke-test intake for vacuum leaks
- Check fuel pressure (rail pressure on DFI)
- Verify MAF and fuel trims
RELATED PARTS
- Ignition coils
- Spark plugs
- Air-oil separator (AOS)