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Discussion Starter · #1 ·
What causes the CO (carbon monoxide) to be higher in your exhaust? I failed state inspection again for the same reason after reconnecting my O2 sensor and repairing a crack in the head-pipe.

I don't just wanna shot-gun parts, but is there anyway I can isolate what's wrong without getting too expensive? I'm leaning towards a bad O2 sensor, b/c my CAT is only 4 years old at this point, 2 of which it sat in the garage. I don't think it's a clogged fuel injector b/c I change my fuel filters often and always use injector cleaner at every 3,000 mile oil change.

Any thoughts / suggestions? Everything else is well within range, but the CO is several times the allowed limit. I'm not happy at all b/c now I can't drive my Jeep anywhere until I get it fixed :(
 

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Have you ran any cat cleaner threw it? A lot of todays cheaper fuels will clog up your cats real bad. That's what happened to the truck. Would fail emissions but ran cat cleaner threw like one or 2 tanks and it passed. And also id try an o2 sensor. Not to expensive don't have much to lose. I think I got one for like 30 bucks at advanced auto or something close to that
 

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CO comes from rich mixtures which points to the O2 sensor or possibly a temperature sensor that is telling the engine ECU that the engine is cold, when it is not. It would help to know what model year and engine you have and all of the actual emission test numbers.

Typically if the engine is running rich and the cat is working you get a lot of temperature rise in the catalyst because it is trying to burn the excess fuel. I don't know about Jeep's specifically but there are a lot of car fires started due to this condition.
 

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Discussion Starter · #5 ·
Well I can't add any cleaners to my tank now that I can't drive the Jeep, it would take forever to burn threw 2 tanks of gas at idle lol. I will look into the O2 sensor furthermore, it is a few years old but I'll start there. Thanks for the troubleshooting guide Joker, that's some really good info. I've had the Jeep now for 10 years and I never replaced the MAP sensor, so maybe I'll toss one of them in too and see what happens.
 

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Were you overdue for inspection when you failed? Because if not, you have till the last day of the month on your sticker. I am guessing since you posted yesterday, you probably expire in October? If so, you have a little while, maybe 3 weeks to run a few tanks through the Jeep. Get some cleaners in there and hope for the best before you toss money at it.
 

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Check O2 again and check to make sure your manifold gasket isn't leaking (from past experience they don't just test in the pipes but all around vehicle)
 

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Discussion Starter · #9 ·
Were you overdue for inspection when you failed? Because if not, you have till the last day of the month on your sticker. I am guessing since you posted yesterday, you probably expire in October? If so, you have a little while, maybe 3 weeks to run a few tanks through the Jeep. Get some cleaners in there and hope for the best before you toss money at it.
My Jeep sat for 2 years while I was working on it so it was 2 years overdue lol. When I got it re-registered, I had 2 weeks to get it inspected. I failed the 1st time and got till the end of the month, (September). Failed again so now I can't drive anywhere without getting pulled over, they said "You have to be driving to the inspection station or a repair facility, that's it." So I'm kinda beat for driving around burning a cleaner in my fuel tank for now.

Check O2 again and check to make sure your manifold gasket isn't leaking (from past experience they don't just test in the pipes but all around vehicle)
Since I passed the other areas of inspection, they are just checking the exhaust pipe at the end, they have that probe they lay just behind it. I will 2x check for leaks though.
 
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