Catalytic converter code

RICHARD FARMER

MEMBER
2010 CADILLAC DEVILLE DTS
4.6L
V8
FWD
AUTOMATIC
210,000 MILES

Catalytic converter code still on after catalytic converters have been replaced. GM dealer says the aftermarket catalytic converter are the problem.

Thursday, January 19th, 2017 AT 9:58 PM

3 Replies

SATURNTECH9

MECHANIC
30,869 POSTS

I have never had a issue with an aftermarket catalytic converter not fixing a cat code. If that was the problem. What is the exact code numbers you have not code descriptions?Also, what catalytic converter or catalytic converters were replaced?

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Thursday, January 19th, 2017 AT 10:43 PM

RICHARD FARMER

MEMBER
2 POSTS

Thanks, the code is P0420 Catalyst System Efficiency Below Threshold (Bank 1) and both catalytic converters where replaced.

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Friday, January 20th, 2017 AT 9:11 AM

SATURNTECH9

MECHANIC
30,869 POSTS

I just had a bank two catalytic converter low efficiency code on a Ford F150. The way I knew the catalytic converter was bad was I watched the the up stream and down stream o2 sensor readings for bank two. Both sensors were about equal readings at about 2500 rpm. How did they determine it was the aftermarket catalytic converter? Also, if you changed the bank two catalytic converter as well and the catalytic converters were not compatible. I would think it would set a P0430 bank two catalytic converter on efficiency. What brand and part number were the catalytic converters?

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Friday, January 20th, 2017 AT 9:56 AM