failed smog

1999 CHEVROLET SUBURBAN
200,492 MILES • V8 • 4WD
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CHEVY BEAST
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  • 2 POSTS
have a 1999 chevy suburban took to have smog-ed failed because of the o2 sensor and the knock sensor replaced boths sensors light still on. reset the computer, drove around town. the light didn't come back on. took to have rechecked for smog, fail with the same code errors. shop ran a dynogstic test at around 11:30am and at 4;30pm still on machine. called us before 6pm and said the computer was out they couldn't get a reading. if the computer was out would I have been able to drive it to the shop?
Jul 14, 2011 at 2:22 PM
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WRENCHTECH
  • ✓ASE Certified Mechanic
  • 20,761 POSTS
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Sure, there are a million different ways for a controller to be faulty. That doesn't always mean totally inoperative.
Jul 14, 2011 at 2:38 PM
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CHEVY BEAST
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if the computer was out how did they get a reading on the smog the second time, and than nothing on the diagnostic test.
Jul 14, 2011 at 2:45 PM
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