P0420 -somebody posted a list of diagnostic codes once on these forums so i have them in a word file.

here is the basic description of P0420; Catalyst System Efficiency below Threshold - Bank 1

this may be what your mechanic is going by but thougt i'd post it just in case.

Answered by artisannm
3 questions asked

Artisannm: Thanks for the reply. I was able to determine that the code was for the catalyst system below efficiency (bank 1), the problem is that nobody, even the dealership service technicians dont know how to fix the problem. They are baffled even after replacing the obvious trouble makers. Does anybody have any additional suggestions as to what else we might try looking at to fix this problem?

Barb

Response from squigley68
2 questions asked

I have a 2000 Mazda Miata that has the P0420 Catalyst System Efficiency Below Threshold (Bank 1) trouble code. Has anyone figured out what exactly to replace or repair to clear this code?

Answered by idrive4alivin
0 questions asked