I recently bought a 03 Mazdaspeed with 10,000 original miles. It currently has a 2 stage boost controller, Tein SS coilovers, and a Greddy SP exhaust with downpipe installed. The check engine light came on and the code being shown is P0421 - Warm up Catalyst Efficiency Below Threshold (Bank 1). Would anyone happen to know what this code means, and the possible fix?(huh)
Thanks for helping out the new Mazdaspeed Owner.
Thanks for helping out the new Mazdaspeed Owner.