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post #1 of (permalink) Old 09-15-2003, 11:54 PM
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Check Engine Light, P0430 catalyst efficency low.

'96 Suburb 4x4 w/5.7. Anybody besides me been fighting this problem? I've cleared it 4-5 times. (Bank 2) Sometimes it comes on in a day, sometimes in a week. It always came on after a long highway drive until I changed both RH O2 sensors. Then it went about 45 miles and came on during intown driving. Be aware that this "can" be caused by an "upstream" problem. Doesn't mean it's a bad converter. Truck has 200,000 and runs like a top. No drivabilty problems at all. Gets 18 mpg highway..yadda yadda..yadda. Everybody I've talked to says this can be a real pain in the ass. Any history?

Ok...for all those who want to know or care. I put a new Y-pipe/converter on tonight. Come to find out the cat for the RH side (bank 2) was knocked out. To go along with my original suspesions, the exhaust always had a nice little "cackle" to it, and.....there was RTV on both "donut" seals and the rear flange. Instinct told me someone had been in there. Anyway..called the previous owner and his repair shop, of course they all claim ignorance of any idea on how "that" happened. What bugs me is why the MIL sometimes would not come on for a week. With OBDII, it should've come on within about 10 miles. Oh well, I'm keeping my fingers crossed that this repair keeps the light out.
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