Emission codes
P0430: catalyst system efficiency below threshold (bank 2)
Engines with two exhaust banks have a converter on each side, each judged on its own. P0430 is the bank 2 verdict: the side without cylinder 1 is no longer cleaning the exhaust well enough.
P0430: can I drive, and what will the labor cost?
Estimated labor, replace downstream oxygen sensor (bank 2 sensor 2)
$33 to $110
| Labor time (estimate) | 0.3 to 1 h |
| Rate used | $110/h |
| Technician wage, United States (average) | $27.13/h |
| Moderate: fix within weeks Drivable; it will fail an OBD inspection, and a bank 2 cause (misfire on that side) should be ruled out. | |
Labor only: parts and the diagnostic fee are not included. Hours are our estimate for a typical car; book times vary by model. Wage: BLS, May 2025.
P0430 is the generic OBD-II code for "catalyst system efficiency below threshold, bank 2". It is set the same way as the bank 1 code: the engine computer compares the oxygen sensor ahead of the converter with the one behind it, and when the rear signal starts to follow the front one, the converter's oxygen storage has fallen below the limit. Only V engines and some others with split exhausts have a bank 2. On its own, P0430 points to that side: the bank 2 converter itself, the downstream sensor on that bank, a leak in that side's exhaust, or a misfire or rich running on bank 2 cylinders that has damaged it. If P0420 is stored too, both converters have aged together, which suggests high mileage or an engine-wide cause such as oil consumption. The car drives normally but fails an OBD inspection. On many V6 front-drive cars the rear-bank converter is part of the manifold, which takes longer to replace.
Is this repair still under the emission warranty?
Catalytic converter
Likely covered: ask a dealer
| Federal emission warranty, 8 years or 80,000 miles | within |
Age counts from delivery to the first buyer; whichever limit comes first ends the warranty. Your warranty booklet lists the covered parts and prevails.
Codes, rules and labor data checked by Radif Partners · Editorial policy · Method and sources
P0430 at a glance
| Code | P0430 |
| Standard description | Catalyst System Efficiency Below Threshold (Bank 2) |
| System | Exhaust emission controls |
| Severity | Moderate: fix within weeks |
| Common symptoms | usually none, emissions test failure |
Why one bank fails first
The two converters share the engine's age but not always its stresses. A coil that misfired for months on one bank, an injector that leaked, or a valve seal letting oil into one head can wear out one converter well before the other. Looking at the misfire history of the cylinders on bank 2 is therefore part of the diagnosis. If a code such as P0174 has been set on that bank, its lean or rich running may also have played a part.
Manifold converters
To heat the converter quickly after a cold start, many makers place it right at the exhaust manifold. On a transverse V6, the rear one sits against the firewall, and replacing it can mean removing other parts and dealing with seized studs. The labor table gives 2.5 and 5 hours for that case, against 1 and 2.5 for a converter that bolts into the pipe further back.
Warranty and legal parts
The federal rules cover catalytic converters for 8 years or 80,000 miles against defects (40 CFR 85.2103); the tool on this page checks your car's age and mileage against that and the California limits. In California, an aftermarket replacement must carry an approval for your vehicle. A converter that fails because of an engine fault may be refused under warranty, which is one more reason to fix the cause first.
Likely causes of P0430, in order
| Cause | How often |
|---|---|
| Bank 2 catalytic converter worn | most frequent |
| Bank 2 downstream oxygen sensor | frequent |
| Exhaust leak on the bank 2 side | frequent |
| Misfire or rich running on bank 2 | frequent |
P0430 repairs and labor time
| Repair | Labor (estimate) | At $110/h |
|---|---|---|
| Replace downstream oxygen sensor (bank 2 sensor 2) | 0.3 to 1 h | $33 to $110 |
| Replace catalytic converter (direct-fit) | 1 to 2.5 h | $110 to $275 |
| Replace converter built into the exhaust manifold | 2.5 to 5 h | $275 to $550 |