P0431moderate severityPowertrain
Warm Up Catalyst Efficiency Below Threshold Bank 2
on 2009 Audi TT 3.2L V6 · AWD
What this code means
Bank 2 warm-up catalyst efficiency is below threshold.
Symptoms
- Check Engine Light
- Failed emissions
Common causes
- Worn catalyst
- Rich running during warmup
- O2 sensor issue
Diagnostic steps
- Monitor catalyst
- Compare O2 signals
- Check exhaust
Repair notes
Replace warm-up catalyst if confirmed.
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