Post Catalyst Fuel Trim System Too Rich (Bank 1)
Long-term post-catalyst fuel trim on bank 1 has reached its rich limit. The downstream sensor sees more reductant than expected, often pointing to a degraded catalyst that no longer stores oxygen, or a failing downstream sensor biased rich.
Affected components
- Oxygen sensor downstream
- Catalytic converter
Common causes
- High likelihood: Catalyst oxygen storage exhausted
- Medium likelihood: Downstream sensor biased rich
Possible symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.