semperfiws6

I Got This Code On My 98 T/a Ws6. It Narrows It Down To The O2 Sensor Or The Cat (bank 2). Anyone Ever Had This Code And Know For Sure?

2001NBMZ28

You can try swapping the rear 02's from side to side and see if it throws P0420, but most of the time it's the cat.

MasnarT

I just had the #420 and it was the driverside cat and in june I had #430 otherside, and had both done under warranty.....runs alot better

horist

ditto

swap O2s and see if the code follows ("reset" the PCM after swapping)

if it follows... then it's a bad o2 sensor... if not it's a bad cat (likely bat cat)

now... if it's a bad cat... GM recently extended the warranty on cats due to problems... (EPA requires 8 year/80k mile... i think GM extended to 10k/100k mile) ... though don't know if it applies to 98s ... I know 00-02 were covered

semperfiws6

i was pretty sure it was the cat. unfortunately the warranty doesnt cover 98's. i appreciate the help.