Originally posted by Geddup Noise:
Then the shop, after running the analysis, told me it was the catalytic converter. so i'm not exactly sure if it is the main cat or the precats that are the issue here.
The main cat is not monitored, so the pre-cats are indicated. As Big Jim said, other things can cause this code.
If I was spending the money, here is what I would do:
1. Clean the Throttle Body (TB) and be certain to clear those passages behind the TB gasket. They get gunked up really bad. Clean the throttle plate while there.
2. Do an upper intake cleaning without removing the UIM. Berryman B-12 has been known to 'scrub' the precats a bit & in at least one case I read in these boards the P0420 code went away.
3. If when you do the TB cleaning the EGR passages are gunked up and you have a silvery metal body DPFE, swap it out for a new black plastic body DPFE. Under $40 and and easy job. Two bolts, one electrical connector, & two vac hoses.
Once those are done, reset your PCM & the code may not return. If it does return, then it's time to consider pre-cats.
Must be that jumbly-wumbly thing happening again.
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