Ok I got a SES light today, Got it read and it came back with P0420 as the code.
I checked my FSM/ESM and that code is for the Three-way catalyst, which going by what the FSM/ESM says and shows in a diagram, one of the two pre-cats is no good, there is acouple other possibilities listed but im leaning more towards the cats. Anyone else ever have this code? And if so, what ended up being the exact problem? thanks in advance

 

there is a TSB for this infamous P0420 code. Go to the dealer and they'll update your ECU under the federal emissions warranty.

now they might try to run the $85 diagnostic fee past you, but when they find that the code is covered under the warranty, they SHOULD waive the fee

 

thanks for the info, but since my max is Cali emissions does the TSB still apply?

 

federal emissions aka US gov't (EPA) as in 90k miles...

i believe this only applies to cali spec cars

if they try to charge you for this, PM me and i'll send you a copy of my service writeup

 

thanks again...