Can anyone help me, I got a engine check light. went to autozone and had the code check. Got a Code:

P0421
warm-up Calalyst efficiency below threshold (bank 1)

Can anyone help me, with this? Can i fix it myself. Mazda dealer no help.

 

check for exhaust leaks

if that is fine then any of the two O2 sensors are bad

 

when you say exhaust you mean muffler? And if its not the exhaust and 02 sensor is it hard to replace myself?

 

He probably means anywhere from exhaust manifold to tailpipe.