Secondary air monitor, not passing California smog test?

Tiny
JBARAKOS
  • MEMBER
  • 1999 CHEVROLET 1500
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 90,000 MILES
I took it for a smog test, and it had four monitors not cleared it has no other codes, but they wouldn't pass it. It had a broken fuel gauge sending unit and I read that if the fuel gauge is broken it may not allow monitors to clear so I replaced the sending unit and three of the monitors cleared but the secondary air system did not. I was told that it needed to be driven and go through a bunch of drive cycles to clear it, so it was driven for about 30 miles in town miles and forty highway miles with mixed speeds and still it isn't clear. I keep reading about checking for check valve functioning, replacing the O2 sensors even relacing the thermostat to a hotter one, I can hear the pump working but my question is, is there a way to find the cause that a backyard mechanic can do aside from just randomly replacing parts or should I take it to the dealer or a specialty shop? Or will they just start randomly doing what I would do?
Wednesday, August 3rd, 2022 AT 7:53 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Hi,

When you say four monitors weren't set, are you referring to an emissions system that hasn't completed a drive cycle? I noticed the mileage you drove and the conditions. It may simply require more of that same until it resets. If the monitor is incomplete, it will stay that way until a specific number of things happen. If the system isn't working, it will show complete on the monitor, and you should have a diagnostic trouble code indicating a problem.

Let me know.

Joe
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Thursday, August 4th, 2022 AT 5:17 PM

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