The same catalyst efficiency problem as P0420, but on bank 2's catalytic converter. On many V-configuration engines each bank has its own catalyst, so it's entirely possible for one to wear out well before the other.
Symptoms
- Often no noticeable driving symptoms — frequently a check-engine-light-only code
- Possible failed emissions/MOT/TÜV test
- A faint sulfur smell from the exhaust in some cases
Likely causes
- Aging, naturally worn-out catalytic converter on bank 2
- An upstream bank-2-specific problem (misfire, rich mixture) contaminating that catalyst
- A failing bank 2 rear oxygen sensor giving a false reading
- Exhaust leak near the bank 2 sensors
How to diagnose it
- Check for other active bank-2-specific codes (misfires, fuel trim) first
- Compare upstream vs. downstream bank 2 oxygen sensor data with a scan tool
- Inspect the bank 2 exhaust section for leaks near the catalyst and sensors
Typical fixes & cost
- Replace the bank 2 catalytic converter (after ruling out an upstream cause)400–1800 EUR
- Replace a failed bank 2 rear oxygen sensor, if that's the actual root cause80–250 EUR
Code names are compiled from open/standardized SAE and ISO references. Explanations, symptoms, causes and fixes are original. Covers generic (P0/C0/B0/U0) codes only — manufacturer-specific codes are planned for a future update.
AS
Reviewed by Artyom SemenovAutomotive Editor · Fact-checked by Yauheni Kapliarchuk, Editor-in-Chief