Mechanics

TROUBLE CODE P0421

Mazda 626

I have a Mazda 626.2001 4 cyl. Auto. 76K. Check engine light came on. Autozone checked and code P0421 came on. The counter guy suggested a tune-up. I had one in March. Maybe 5K on car since then. The read out states warm-up catalyst efficiency for bank 1 is below threshold. What does that mean and where do I go from here? Thanks
Bill from ohio
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Irish81449
October 20, 2006.



Hi Irish,

Well there are a few things that could be going wrong.

1. The front cat (right under the manifold) might be bad. This can be diagnosed by check the front and rear 02 sensors the see if they are switching at the same rate (ie the cat is bad).

2. There might be a PCM update for this code, but if left too long you might need to replace both the front cat and have the pcm updated.

So my sudgestion is to see a Mazda dealer for this code.

Cosmo

Mazda Tech

Tiny
Cosmo
Oct 20, 2006.
I have been told that Mazda has a 8yr. 80K warranty on their emissions. Is this true? I have reseached and only find said warranty on Miata model.
Bill

Tiny
Irish81449
Oct 20, 2006.
Well that depends on where you are.I am in Canada, here Mazda has a 3 year 80k warrenty on bumper to bumper warrenty, thern a 5 year 100km on their powertrain.

There is however a 7year 128,000km warrenty on some emmision components ie: cats and PCM's (but don't quote me). The bestthing to do is get in contact with your local Mazda dealer. Taking a detailed vehicle repair history with you would be an asset to you at the time of diagnosis as well.

Cosmo

Mazda Tech

Tiny
Cosmo
Oct 20, 2006.