Cel P0421

stewnate

Member
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2008.5 MazdaSpeed 3
With the double bunged dp from turbo xs and the stage 2+FMIC map i shouldnt be getting a check engine light should i??

Warm up catalyst efficiency below threshold (bank 1) is the discription.

anyone have an idea of what this means and what its caused by. I can reset the CEL using the AP but after about 120 miles it comes back on. only during highway speeds too.
 
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