I'm getting a P0420 and P0430. I went to a muffler shop, they fit a camera in there, looked both cats, pronounced them clean bills of health and said to start pulling sensors and replacing them. I've replaced all but one at this point and am still getting the error. Annoyed, I went into FORscan and ran a PCM test with engine on. It reported "Cannot run test, exhaust temperature too high" or something like that. I am getting ready to sell this truck in the summer of 25' and I'd like to clear these errors because they are OBVIOUSLY something that'll affect price and to be honest, I wouldn't buy a truck or any vehicle with cat issues.

 

The codes are for both banks.
They are not errors but fault codes.
What is Cat temp to high?
They normally run in the 800 to 900 degree range after starting and stabilization.
For both banks to be in code fault, something is going on with the engine to cause them to set the codes.
Without more info its difficult to go further with possible causes other than contamination or overheating from Raw fuel being passed out of misfiring cylinders both. Banks.
The Ox Sensors detects low Oxygen levels out of the Cats that sets the codes.
They just maybe at the end of their life after 7 years.
Good luck.

 

Yeah unfortunately I don't have a lot to go on. When I said "temperature too high" - I meant in ForScan. You can run a PCM test on the truck with key/engine on and at the end it runs some kind of sensor test I suppose - and that says "Exhaust Temperature too high not running test". Any idea if these direct fit or weld on cats are worth it? Magnaflow sells some cheap assed ones. I'm not looking to spend thousands on this, I'm probably going to sell this thing in the summer.

 

1) go into mode 6 data and you can scroll down to a section with cat health - it will tell if the oxygen saturation capacity is out of spec. Thats what happened with my truck. if this comes back bad then no need to bother with the key on, engine on test. I bought a set of SPD catted down pipes for my 12 and it's worked fine. Im not using any spacers or non foulers and I get no codes (double stacking the non-foulers and actually caused an air leak and made it throw codes).

2) if you read the notes prior to running that test I believe it tells you the conditions to use. I know you cant run it immediately after starting the vehicle is its not at full operating temp, cant remember if there was any guideline about how warm it should be. Maybe try just letting the truck idle for a bit from cold or let it sit and idle for a bit after driving and see if it will run.