What P0430 means
Identical fault to P0420, but on Bank 2 — the cylinder bank on V6/V8 engines opposite cylinder 1. Your engine has two exhaust paths with two catalysts, and the computer is reporting that Bank 2's converter has fallen below the efficiency threshold.
What you’ll notice
- Usually just the light
- Possible sulfur smell
- Emissions test failure
Likely causes and repair cost
Broad US independent-shop bands, parts and labour.
Can you drive with P0430?
Same as P0420: drive normally, fix before your next emissions test, and take it more seriously if it arrived alongside misfire or oil-burning symptoms.
The misdiagnosis to avoid
On V-engines, replacing the wrong side. Bank 2 is the side opposite cylinder 1, and which side that is varies by manufacturer — shops occasionally quote (or replace) the Bank 1 converter for a Bank 2 code. Ask which bank is which on your engine.
Describe what it’s doing in your own words and the symptom checker gives you a safe-to-drive verdict, ranked causes with costs, and notes to take to the shop — free, no sign-up.
Read the code yourself
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Check price on AmazonQuestions people ask
Why did only one bank's catalyst fail?
Each bank has its own injectors, coils, and sensors, so an upstream fault on one side (a misfiring coil, a leaking injector) poisons only that side's converter. If Bank 2's catalyst died young, look for what's different about Bank 2 — often the real culprit is a cheap ignition part on that side.
Both P0420 and P0430 together — what does that mean?
Both catalysts failing simultaneously is unusual unless the car is genuinely old; a shared cause is more likely — chronic rich running, oil consumption, or simply lazy original sensors. Paired codes strengthen the case for upstream diagnosis before any converter spending.