Catalyst System Efficiency Below Threshold Bank 2

What this code means

The Bank 2 catalytic converter is not performing efficiently. Same as P0420 but for Bank 2.

Symptoms

• Check Engine Light
• Failed emissions test
• Possible sulfur smell

Common causes

• Worn catalytic converter
• Exhaust leak near downstream O2
• Faulty O2 sensor Bank 2
• Misfire damage to catalyst
• Oil contamination

Diagnostic steps

1. Compare upstream/downstream O2 waveforms Bank 2
2. Check for exhaust leaks
3. Test downstream O2 sensor Bank 2
4. Check for misfire codes
5. Inspect for oil consumption

Repair notes

Same approach as P0420 but for Bank 2. Replace catalyst if confirmed failed.

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