P0430 OBDII code

RAILCARENG

MEMBER
1997 CHEVROLET TRUCK
V8
2WD
AUTOMATIC
170,000 MILES

Hello there.
I have a 1997 C1500 2wd Pickup in which the check engine light is on. The code reported from my handy dandy OBDII reader is P0430 - Cat Sys Below eff Bank 2.
I have narrowed this to an O2 sensor or the Cat.
Can you give me some direction if I am on the right track or completely derailed.
Thanks for your help
Al

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

That is correct. There could be a few issues with this so I am attaching the testing below but here are a few guides that will help with this:

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Basically, what this is saying is that the upstream o2 sensor is sensing a certain amount of oxygen in the exhaust. When the oxygen content is low the assumption is made that there is more fuel. So, the downstream sensor needs to show that this amount of oxygen has come up to an acceptable level which means the converter is reducing the amount of fuel in the exhaust and doing its job.

So, this means the upstream or down can be reading inaccurate causing the PCM to think it is not reducing the fuel enough.

Please run through the testing below and that will get us to the solution.

Let us know what you find. Thanks

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