Parts
$50–2000
P0430 — Catalyst Efficiency Below Threshold (Bank 2)
CAUTIONIs it safe to drive? Same as P0420 but the other bank. Driveable; verify before replacing an expensive cat.
What P0430 means
The Bank-2 catalyst isn't converting efficiently — the rear O2 mirrors the front too closely.
Most likely causes (in order)
- Failing downstream O2 sensor
- Exhaust leak near the rear O2
- Worn catalytic converter
- Upstream misfire / fuel-mixture problem
Symptoms you might notice
- Check-engine light
- Possible mild economy loss
What to check first
Same playbook as P0420: rule out the O2 sensor and exhaust leaks, fix upstream causes, then judge the cat.
Repair cost & difficulty
Labor
0.5–3 hr
Difficulty
Moderate