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Code P0420 - What to do? #426430 Mar 26, 6:33pm Mar 26, 6:33pm
Joined: Nov 2002
Posts: 489
Hampton, VA
CRBN BLU OP
Senior Member
2002 Toyota Celica GT
CRBN BLU OP

Senior Member
2002 Toyota Celica GT

Joined: Nov 2002
Posts: 489
Hampton, VA
Code P0420 - What to do?
Ok, so I'm driving down interstate and my CEL comes on. Not the first time in the past month. But I did stop this time to get it checked.

Code P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
-Gas leakage on exhaust system
-Open or short in heated oxygen sensor circuit
-Heated oxygen sensor
-Three-way catalytic converter

My car only has 63,xxx miles on it. The AutoZone guy suggested the O2 sensor. Any one else get this code? What can be done to test the different aspects of the possibilities and how can I fix it?


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Re: Code P0420 - What to do? [Re: CRBN BLU] #426431 Mar 26, 11:50pm Mar 26, 11:50pm
Joined: Dec 2004
Posts: 15
Rochester, NY
Shadow_GTS
Member
Shadow_GTS

Member

Joined: Dec 2004
Posts: 15
Rochester, NY
I had the same code after i installed my TRD exhaust. One of your o2 sensors needs to be replaced or it has caused a minor leak around that vacinity. My problem was that my brother stripped my o2 sensors threads and it was leaking air at that port throwing that very same code. Luckily he is a engineer and borrowed a tool and die kit from work and retapped it. No problems since.

Re: Code P0420 - What to do? [Re: Shadow_GTS] #426432 Mar 27, 1:34am Mar 27, 1:34am
Joined: Dec 2004
Posts: 401
Arkansas
maingear
Senior Member
2002 Toyota Celica
maingear

Senior Member
2002 Toyota Celica

Joined: Dec 2004
Posts: 401
Arkansas
Get a scanner that can read the O2 values while the engine runs. Let the engine temp rise and check the voltage fron the O2 with the scanner. If there is voltage than you can scratch the short/open in the circuit.


If I'm not mistaken, Isn't the emission systom on this car covered under a 100,000 Mile warranty??? confused

Re: Code P0420 - What to do? [Re: maingear] #426433 Mar 27, 2:23am Mar 27, 2:23am
Joined: Feb 2004
Posts: 965
Orange County, CA
2000 White Toyota Celica GT morris
BerraquĆ­sima!
2000 Toyota Celica GT
morris
2000 White Toyota Celica GT
BerraquĆ­sima!
2000 Toyota Celica GT

Joined: Feb 2004
Posts: 965
Orange County, CA
Originally Posted by morris
I got the same last october...
but my light comes and goes by itself... sometimes within a few miles, others, withing hundreds. I'll take my car for diagnosis (besides: brake recall, oil change- they're so nice a my toyota dealer- and other minor maintenance... ) and see what happend... I think the problem is the O sensor...

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Re: Code P0420 - What to do? [Re: morris] #426434 Mar 27, 6:38pm Mar 27, 6:38pm
Joined: Jun 2004
Posts: 1,696
Tampa, Florida
Polykarb
Metal Storm 2040
2000 Toyota Celica
Polykarb

Metal Storm 2040
2000 Toyota Celica

Joined: Jun 2004
Posts: 1,696
Tampa, Florida
yeah i've been running my GTS with cel on for like a month now with 6 thrown codes as well as the one mentioned in this thread. confused confused


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