2003 GMC Sierra Catalytic Converter problem

2003 GMC SIERRA
170,000 MILES • 4.3L • 6 CYL • 2WD • AUTOMATIC
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JASONALL
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My check engine light came on showing catalytic converter bad bank one. I replaced the whole Y-Pipe including both catalytic converters. I have reset the the light twice and driven around 250 miles already and the light is back on showing the same code?!?!? Am i doing something wrong here? My inspection is out and I need some advice quick. Is there a trick to getting the computer to reset? HELP!!!
Jun 10, 2014 at 6:03 AM
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WRENCHTECH
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Did you use OEM parts from the dealer?

Are there any exhaust leaks in the left pipe, even small ones?
Jun 10, 2014 at 8:51 AM
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JASONALL
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I ordered an after market y pipe and it didn't fit quite like the factory.. but it fit. We did have some trouble getting it to seal though. I cant hear an obvious leak but that doesnt mean its not. Do you think that might be my problem?
Jun 10, 2014 at 9:37 AM
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WRENCHTECH
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Either one of those things could be your problem. The aftermarket parts often don't work and an air leak will effect the sensors.
Jun 10, 2014 at 2:26 PM