Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, new and have a p0420 / p0430 codes in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; i have an 04 CTS with the 3.6 that keeps throwing those 2 codes and has what almost seems like ...
i have an 04 CTS with the 3.6 that keeps throwing those 2 codes and has what almost seems like a miss/pop in the engine at idle, it is not all the time just only when it idles other than that it runs out great and fine no stuttering. Upon looking into the cats I find that they have the "visual inspection" cats that a copy online sells so they are deffinately not plugged. I thought they were plugged causing what almost acts like a backfire or the engine loading up. any ideas? thanks
I believe those codes are rear o2 codes for cat converter. If the o2 sensors are good, I would have to think cats. How many miles on the caddy? I believe the cats are covered under their own warranty for something like 80k miles \ 8 years if I'm not mistaken. Maybe someone can double check that.
check the full exhaust system from head to tailpipe for cracks or holes, if its not that those 2 codes trigger when the cats have lost efficiency for storing oxygen so cats are bad, if you get any errors after new cats, sometimes p0054 or P0060 that will be bad o2 sensors, whoever does the work has to be careful not to disturb the sensors to much when removing them from the old cats, if in doubt get new ones and replace cat and sensors while your in that area.
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it has visual cats only they are the ones a company online sells. they are just straight through pipes that look like stock convertors. i haves those codes but would they make the car idle odd i guess is what im wondering. right now after it warms up i get an odd idle like a miss but it never trips a code for an engine miss
Since you have no cats, per se, I would imagine the ECM is having difficulty with the O2 readings. Since it expects a certain difference between the pre and post O2 values and there is none, it's not happy. Only replacing the cats with real ones or adjusting the values in the ECM (doubtful at best) will you be able to alleviate the ECM's displeasure. Plus that awful exhaust smell on a Caddy is "just not right" jkjk
I have exactly the same problem now. It started with one code at first (P0420), which if I remember correctly is Bank 1. Anyways, I thought I was been smart by installing an used Cat (trying to save money). The used cat seem to be in good condition but now I have the code for both Cats (P0420 and P0430). I am just going to buy new OEM Catalytics. Is there a better place to buy OEM for a lower price than the local GM/Cadillac "Stealer" (aka Dealer)
By the way I have a CTS 3.6L with 140,000 miles for reference.