P0420 DTC - Check engine light

SQUIGLEY68

MEMBER
KIA

2001 Kia Rio: The check engine light has been on for a while now, and I have the P0420 Diagnostic code coming up on my scan gauge. The dealer has replaced the front O2 sensor, the MAF, and the catalytic converter. Could the problem continue due to a faulty rear O2 sensor? This problem has both me and my service technicians baffled.

Barb

3 Replies

ARTISANNM

MEMBER
8 POSTS

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.

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Sunday, July 30th, 2006 AT 9:14 AM

SQUIGLEY68

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3 POSTS

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

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Sunday, July 30th, 2006 AT 9:21 AM

IDRIVE4ALIVIN

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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?

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Tuesday, May 15th, 2007 AT 9:28 PM