Mazda Millenia This sedan, the flagship luxury sedan, offers both a naturally aspirated and supercharged model, so you can have your luxury, and, if you have a need for speed, big horsepower.

P0421!?!?!?!?!?!

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  #1  
Old 05-24-2011, 08:57 PM
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Default P0421!?!?!?!?!?!

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?
 

Last edited by santa6; 05-24-2011 at 09:57 PM.
  #2  
Old 05-25-2011, 07:32 AM
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Originally Posted by santa6
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?
 
  #3  
Old 05-25-2011, 11:10 AM
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Default Warranty

Originally Posted by keninn
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.
 
  #4  
Old 05-25-2011, 11:21 AM
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Default Warranty

Originally Posted by keninn
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. Just called the dealer - warranty is straight 12 mon/12,000 miles, even for cats. Their price for new pre-cat is $846.72.
 
  #5  
Old 05-25-2011, 11:23 AM
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Default Sensor

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)?
 
  #6  
Old 05-25-2011, 01:26 PM
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Originally Posted by santa6
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
 
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