Catalyst System Efficiency Below Threshold (Bank 2)
Same condition as P0420 but on bank 2. On engines with one shared catalyst per bank, P0420 and P0430 appearing together usually point to age rather than damage.
Affected components
- Catalytic converter
- Oxygen sensor upstream
- Oxygen sensor downstream
Common causes
- High likelihood: Catalyst aged or contaminated
- Medium likelihood: Downstream oxygen sensor drift
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.