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Old 03-19-2012, 11:16 PM   #1
loganInaYj's Avatar
Join Date: Sep 2011
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Code 21 help

Code 21 : what should I start with? Replacing the o2? I also have a crack in my exhaust manifold. A good sized one. The jeeps running great but won't pass smog . Could be cause of this problem? Any help would be appreciated

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Old 03-20-2012, 07:21 PM   #2
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Fix the exhaust first. Any O2 will affect the O2 sensor. Good luck, Ron

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Old 03-21-2012, 01:03 AM   #3
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Originally Posted by Laguna S-3 View Post
Fix the exhaust first. Any O2 will affect the O2 sensor. Good luck, Ron
thanks ron. yeah im gonna start by just welding my manifold first. do you think this could be the cause of it not passing ca smog check?
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Old 03-21-2012, 09:48 PM   #4
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Most likely your crack is letting too much air into your exhaust, and when your o2 sensor reads it, it is spiked off the charts lean. The computer says that can't be right and throws the circuit code, not the lean code. Thats my thoughts anyhow, I could be wrong. Start there, it will need to be fixed anyhow.
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