What does P0430 mean?
Catalyst System Efficiency Below Threshold (Bank 2)
Direct Answer
P0430 is identical to P0420 but applies to Bank 2 — the opposite bank of the engine. On V6 and V8 engines, each bank has its own catalytic converter. The diagnosis and repair process is the same as P0420.
Common Symptoms
- ✓Check engine light on
- ✓Failed emissions test
- ✓Possible sulfur smell
- ✓Slight MPG reduction
Common Causes
- 01Failed Bank 2 catalytic converter
- 02Faulty Bank 2 downstream O2 sensor
- 03Oil/coolant contamination
- 04Prior misfires on Bank 2
How to Fix P0430
Test the Bank 2 downstream O2 sensor
Rule out a false reading from a faulty sensor before replacing the converter.
Inspect for contamination
Check for blue or white exhaust smoke on Bank 2.
Replace Bank 2 catalytic converter
Use an OEM-quality converter for best results with emission-sensitive ECMs.
Frequently Asked Questions
If I have both P0420 and P0430, do I need to replace both catalytic converters?
Not necessarily at the same time. Diagnose each bank separately. However, if both converters have the same mileage and one has failed, the other is likely close. Many shops recommend replacing both for economy of labor.
Estimated Repair Cost
$150–$2500
Same range as P0420. Some V8 vehicles require both converters at once.
Safe to Drive?
Yes — with caution
Safe to drive but will fail emissions testing.
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