CEL came on again today

lionseye640 · **Posted:** Wed Feb 04, 2009 12:19 pm

Here's the background info: '05 3.7L V6 with around 39K on it - around 2 weeks ago the CEL came on & we replaced all 4 O2 sensors (the computer said all 4 were reading off).

Today, the CEL came on again, was told that it was "deficient catalytic converter". Then, they kept the computer attached to the KJ with it running to see if anything slipped. Nothing did & they say it's testing as "efficient catalytic converter" now.

What gives? Any ideas why this would be happening?

lionseye640 · **Posted:** Wed Feb 04, 2009 12:48 pm

Yeah, there was heet being run through, but it's been filled up with gas from almost empty twice now, and no problems until now

I kinda thought if there was a problem, it would've manifested itself already, or the cat would have a constant code

tjkj2002 · **Posted:** Wed Feb 04, 2009 9:16 pm

lionseye640 wrote:

Yeah, there was heet being run through, but it's been filled up with gas from almost empty twice now, and no problems until now

I kinda thought if there was a problem, it would've manifested itself already, or the cat would have a constant code

Cats will not throw a constant code since there are no sensors on the cats.The downstream O2 sensors monitor the cats efficiency by comparing there readings to the upstream O2 sensors.Now when you get those efficiency codes it does not mean 100% of the time that the cats are bad.But in your case you ruined your O2 sensors which in turn ruined your cats,it will not happen overnight,by using to much additives like heet.If you need to use stuff like heet it's time to buy gas from a better place even if it is 5 cents more expensive.My KJ has always started without any of those aids,even in temps reaching -35degrees.Now I do once a year use SeaFoam,occasional use(like once a year) is okay and is very beneficial,just remember to change the spark plugs afterwards since they will get fouled.

CEL came on again today

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