Engine code P0420 Bank 1

mazda
rx-8

#1

Is this a sensor(s) and/or the catalytic converter that needs replacement?


#2

Probably, but you should follow the troubleshooting flowchart for that code for your car to be certain before throwing parts at it.


#3

Try the O2 sensor(s) first. They are much less expensive than a new cat. There should be a trouble-shooting procedure accompanying the explanation for this code. Follow the procedure.