If you recognize my post name you might know I have put $6000 into a car I paid $5000 for and is now worth about $3000. This Milly now has all new Cats(a year ago), all new timing system(a year ago), all new plugs(the correct NGK plugs), 3 new coils, 2 new axles, one new front sway bar, new trans filter and pan gasket, new oil cooler seal, new ABV vent & vacuum solenoids and probably some other items I can't remember.

I am currently working through getting the A/C working again and my son drives it home from work tonight(it's his car) and the @#%^%$#@ CEL is back on - I think my heart stopped for several seconds.

First - if you're a Mazda employee out there - .........never mind.

It now has the P0421 code for "Bank 1 warm up catalyst below threshold". There is no way in #@^#@^ hell that I am spending a dime on more cats. Could this be a bad sensor somewhere? The car seems to run fine with no misfire at all.

When I had these two pre cats replaced in June of 2009, I paid $1,600 + for the two parts(no labor in that number). Any chance there is a good warranty on these parts?




Keninn, tell me it's something simple - please. I just read in another post that a Mazda bulletin TSB 01-003/01 says something about sensitive O2 sensors. Given that there is only about 10,000 miles on these new catalytic converters could it be a sensor problem?

there is a pretty stiff warranty on cats. fed mandated. i think it's like 50k/5 yr? were these genuine cats?

Yes, according to the receipt from the Mazda dealer that did the work, they were genuine Mazda parts.

Yes, according to the receipt from the Mazda dealer that did the work, they were genuine Mazda parts. Just called the dealer - warranty is straight 12 mon/12,000 miles, even for cats. Their price for new pre-cat is $846.72.

I won't be spending that kind of money anymore on this car. Is it worth a try to change out a sensor, if so, which one(s)?

check your pm first