P0431
PowertrainCatalystmoderate severityWarm Up Catalyst Efficiency Below Threshold Bank 2
What P0431 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
Where to start: Replace warm-up catalyst if confirmed.
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