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swing4terps 02-12-2013 09:28 PM

P0430 there and gone?
So last Thursday I was driving home and my check engine light came on. Only code was the one mentioned above. Conveniently I had to have my emissions done by this past Saturday, so the code caused me to fail. Was leaving school tonight and started her up and my check engine light did not come on. I did not reset anything. I did some reading on other threads and the consensus seemed to be that it is likely not an O2 sensor problem with this code and the cat must be replaced to correct. My muffler has been done for a while now; rusted out inside and sounds like crap. So I had been looking into prices for a new cat and muffler.

With the CE light going out on its own, am I still looking at a cat problem? Possibly an O2 given this? Thoughts are appreciated.

JFD328 02-12-2013 09:31 PM

Re: P0430 there and gone?
do a search for "P0430"

JFD328 02-12-2013 09:31 PM

Re: P0430 there and gone?
what i have read is that it might be an O2 sensor.

jeepgcoman 02-12-2013 11:02 PM

Re: P0430 there and gone?
Theory of Operation

The State of Change (SOC) catalyst monitor uses the signals from both the upstream and downstream O2 sensors to detect aging of the catalyst. Based on the fact that when a catalyst ages, it loses some of its Oxygen Storage Capacity (OSC). As a result, part of the untreated exhaust gases can breakthrough the catalyst and causes the downstream O2 sensor to deviate from its neutral (Stoichiometric) position. By observing the activities in the downstream
O2 signal, the degradation level of catalyst can be detected. In general, the higher the downstream O2 sensor SOC value, the more exhaust gas breakthrough and the lower the OSC of the catalytic converter.

When Monitored:

The monitor will run at between 1400 and 2300 RPM. It also runs between 40 and 70 KPA.

Set Condition:

If the final State of Change index is within the calibrated fail threshold. Two trip fault. Three good trips to turn off the MIL.

Possible Causes


swing4terps 02-13-2013 08:09 AM

Re: P0430 there and gone?
So is there a way for me to pinpoint what caused the light to come on in the first place as opposed to just guessing and potentially fixing things that aren't broken?

DannyVtCa 02-13-2013 11:31 AM

Re: P0430 there and gone?
You'd have to get a temp gun and check the operating temps of the cats in and the cats out. If one or both are really dramatically hotter than the other you have a bad cat. Ringing, whistling, rattling noises from cats is bad also.

jeepgcoman 02-13-2013 07:48 PM

Re: P0430 there and gone?
When warmed up they should run ~1200-1500* F, depending on engine load and RPM. Like Dan said, they should both be running at almost the exact same temperature.

swing4terps 02-14-2013 07:31 PM

Re: P0430 there and gone?
Haha guess I can't just wip out my thermometer and measure that. Gonna gave to pay the man I suppose.

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