Check Engine Code
P0430
Catalyst System Efficiency Below Threshold (Bank 2)
Severity: medium
DIY difficulty: 2/5
Typical cost: $40–$2500
What P0430 means
Same diagnostic as P0420, but for the cylinder bank that does not contain cylinder #1.
Symptoms
- Check engine light
- Slight performance/economy loss
- Emissions fail
Likely causes (most common first)
- Aged downstream O2 sensor (Bank 2)
- Failing catalytic converter
- Exhaust leak
- Cat contamination
Can I keep driving?
Medium — drivable but fix soon
Typical repair cost
DIY fixes can start near $40 (parts only). Shop repairs for P0430 typically run up to $2500 depending on the underlying cause and vehicle. Start with the most common cause — Aged downstream O2 sensor (Bank 2) — before throwing parts at it.
Related codes
P0420P0431
Confirm P0430 yourself in 60 seconds
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