P1340moderate severityPowertrain
Misfire Detected Crankshaft Segment Adaptive
on 2009 Audi A6 3.0L Supercharged V6 · AWD
What this code means
The ECU detected a misfire through crankshaft speed variation analysis using its adaptive algorithm. The system has learned the normal crankshaft speed pattern and detected a deviation indicating cylinder misfires.
Symptoms
- Check Engine Light
- Rough running
- Slight vibration at idle
- Intermittent power loss
Common causes
- Worn spark plugs
- Failing ignition coil
- Fuel injector issue
- Compression loss on one cylinder
- Engine mount masking vibration symptoms
Diagnostic steps
- Read misfire counters per cylinder
- Inspect spark plugs and ignition coils
- Test fuel injector balance
- Perform compression test
- Check engine mounts
Repair notes
Replace worn spark plugs and ignition coils; investigate further if misfires persist.
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