P2096moderate severityPowertrain
Post Catalyst Fuel Trim System Too Lean (Bank 1)
on 2005-2011 Audi A6 4.2L V8 · AWD
What this code means
The downstream oxygen sensor detects the exhaust running too lean after the catalytic converter. This usually points to unmetered air entering the system or a fuel delivery shortfall.
Symptoms
- Check engine light on
- Slight rough running or hesitation
- Possible reduced fuel economy
Common causes
- Exhaust leak upstream of rear O2 sensor
- Vacuum or intake air leak
- Faulty downstream oxygen sensor
- Weak fuel pressure or delivery
Diagnostic steps
- Scan and confirm code with live fuel trim data
- Inspect exhaust for leaks near rear O2 sensor
- Check for intake vacuum leaks
- Test fuel pressure and O2 sensor operation
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