Please help! Check engine light is on in my 02 Mazda.?

Lani7829

New member
I drive a 2002 Mazda Protege ES. My check engine light came on this morning and I had the code read at Auto Zone. It's P0421 which means "Warm up catalyst below bank 1." I have no idea what that means but the guy told me it's either the o2 sensor or the catalytic converter. The car drives/performs just fine. If it wasn't for the light I wouldn't think anything was wrong. I am going to have it checked but any tips? How do I know it's the o2 sensor and not the catalytic converter? How much is it to have the catalytic converter replaced? Is Midas any good?
 
easiest way to check and see if a catalytic converter is working is the pipe behind the cat should be much hotter than in front of it. Also get under the car and tap on it. If it has come apart it will rattle. O2 sensors are cheap enough, just replace that first and see if that fixes your problem.

From my experience...midas sucks.
 
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