Can you help me with OBDII code: P0430 ?

[Eschrichtius]

Just an update, still no CEL code. Everything's working great and MPG is back where it supposed to be

 

[kingbilly68]

Bringing this thread back instead of starting a new one. My wife's 08 Yukon threw a check engine light yesterday. Scanned it and got a p0430 code. Is the O2 sensor still the place to start? Or should I plan on a cat? Thanks.


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[Beeker702]

I’ve been fighting P0430 for weeks now on my 2015 Tahoe . I’ve replaced both cats and all 4 oxygen sensors as well as all coils, plugs and wires. Cleared code and it comes back a couple of days later. Truck runs fine just have no clue why it won’t stay off for good. Had the fuels trims reset and that didn’t work

 

[swathdiver]

I’ve been fighting P0430 for weeks now on my 2015 Tahoe . I’ve replaced both cats and all 4 oxygen sensors as well as all coils, plugs and wires. Cleared code and it comes back a couple of days later. Truck runs fine just have no clue why it won’t stay off for good. Had the fuels trims reset and that didn’t work

There are several reasons for a P0430. The most obvious is a failed cat, even a new one. A large exhaust leak can set the code, such as a leaking exhaust manifold.

Aftermarket cats and O2 sensors don't play nice with the computer and they will set varying codes.

Finally, when the troubleshooting guide has been exhausted, it's usually time for a new ECM.

A new cat will often set a code within the break-in period, usually a hundred miles or so.