OBD codes / P0430
P0430
ModerateCatalyst System Efficiency Below Threshold (Bank 2)
You can usually keep driving with P0430 in the short term — it rarely leaves you stranded. But it will not pass an emissions or inspection test, and if a failing converter is the cause it can slowly worsen and hurt performance and fuel economy. Get the cause confirmed before buying parts, since a cheap sensor and an expensive converter set the identical code.
What this code means
P0430 is the Bank 2 twin of P0420: the catalytic converter on the side of the engine with cylinder 2 isn't cleaning the exhaust efficiently enough. The computer compares the oxygen sensors before and after the converter; when their readings look too similar, the converter is judged to be falling down on the job. It most often means a worn-out converter, but a lazy or faulty downstream oxygen sensor, an exhaust leak, or an unaddressed misfire can trigger the same code. It only applies to V6/V8/V-style engines that have two banks.
Symptoms you might notice
- Often no change in how the car drives — just the check-engine light
- Failed emissions or smog test
- Slightly reduced fuel economy
- A faint rotten-egg (sulfur) smell from the exhaust
- Sluggish acceleration if the converter is clogged
What it costs to fix
Typical range: $150–$2,500 · about ~0.5–2.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Downstream oxygen (O2) sensor | $50–$300 | ~0.5–1.5 hrs |
| Catalytic converter (bank 2) | $400–$2,400 | ~1–2.5 hrs |
| Exhaust leak repair (gasket or pipe section) | $20–$200 | ~0.5–2 hrs |
Same split as P0420: an oxygen sensor is the cheap end, the converter the expensive end. Converters on luxury, hybrid, or newer low-emission vehicles — and genuine OEM parts — can run well above these figures.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0430 for my exact vehicle →
Frequently asked
Can I drive with P0430?
In most cases yes, at least short-term — it is not typically an immediate safety risk. The downsides are failing an emissions test and, if the converter is degrading, gradually worse performance and fuel economy. Do not ignore it long-term.
What's the difference between P0420 and P0430?
They're the same fault on opposite sides of the engine — P0420 is Bank 1, P0430 is Bank 2 (the side with cylinder 2). Diagnosis and repair are identical; only the location of the affected converter and sensors differs.
Is it the oxygen sensor or the catalytic converter?
Both set the same code, and that's the problem: replacing the converter when it's really a sensor wastes money. A proper diagnosis — checking sensor data and ruling out leaks and misfires — tells you which before you buy parts.
Will my car pass inspection with P0430?
No. In areas with emissions or smog testing, an active P0430 and its check-engine light are an automatic fail. You'll need to fix the underlying cause and clear the code first.
Seeing P0430 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0430 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.