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Unread 03-10-2010, 05:14 PM   #1
jrdewitt
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2004 TJ Wrangler 
 
Join Date: Mar 2010
Location: SoCal
Posts: 20
Error Code P0420 & P0432 - What could it be???

Got a question i'm hoping you guys can help me out with... Check engine light came on with codes 420 & 432 which translate to "Catalyst 1/1 efficiency below required level" & "Catalyst 2/1 efficiency below required level" respectively. Thought I figured it out when i noticed a broken vac line on top of the engine, but after replacing and reseting the computer the codes popped back up within 55 miles. Thought it could be the spark plugs (come to find out they were the original NGKs from 80K miles ago) so I swapped out the plugs. Same thing within 55 miles. My next thought is replacing the two O2 sensors after the precats, but I figured i'd tap the wealth of knowledge that is JF before I continue to fumble around blindly. Thanks!

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Unread 03-10-2010, 07:04 PM   #2
Gonda
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2000 TJ Wrangler 
 
Join Date: Feb 2010
Location: Michigan
Posts: 9
An exhaust leak can cause both of these codes to set. I would start there. Then I would look at replacing the upstream O2 sensor.

I am assuming you engine runs OK...no misfire. If this is in question, check the plugs and the compression first.
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Unread 03-20-2010, 01:28 PM   #3
jrdewitt
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2004 TJ Wrangler 
 
Join Date: Mar 2010
Location: SoCal
Posts: 20
Just went to the stealership and blew 977.00 on the factory replacement precat/downpipe/cat assembly. Ripped the old one off and looked down the tubes... lets just say it was one of those "Well there's your problem" moments! Only driven about 18 miles since, but could immediately feel and hear the difference! 977.00 is painful, but so is 9mpg and failing smog!
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Unread 07-19-2010, 02:28 PM   #4
jrdewitt
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2004 TJ Wrangler 
 
Join Date: Mar 2010
Location: SoCal
Posts: 20
Just a quick update, passed SMOG with 0 problems... the tech said it was one of the cleanest exhaust readouts he has ever seen.
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