P0431 - on 2003 Mazda MPV -do I need to replace front or rear or both converters?

Question

The O2 readings indicate that the converter needs to be replaced,but I hear guys telling me to replace to rear one not the one by the radiator.

Answer 1

P0431 is warm up catalyst.the one in the back is catalytic the main one but remeber P0431 is intermittent,what it should say is check for exhaust leak, that will set off this to code,a loose 02 sensor will also code this up, or crack exhaust, bad cat are code like below threshold or above threshold.