I have a 2008 H2 as a daily driver. Left it park for two weeks and the battery drained. Charged it back up and drive perfectly. A week later took it in for a smog check and it fail. Smog tech ask me about the battery drained without me telling him. Told me to drive it a bit longer to cycle the computer so he. An do the smog test. Two weeks later took it back and the O2 sensor show up and would not pass smogs again. He told me to drive it mire but still O2 sensor show up. My regulars mechanic tell me it’s a common problem on these GM truck . Is it true ? Any advices on getting it fix

Thanks

 

When the test centers do a smog test they check the computer to see if it has been reset. Having a dead battery actually clears any fault codes in the computer much like if you did a clear/reset with a OBD2 test tool. As a result it fails smog test because the system has not had a sufficient amount of start/stop cycles or mileage accumulated since the reset (dead battery). This was something that was instituted to prevent someone from doing a reset to clear an actual fault then quickly running through a smog test to mask an actual problem. The mileage required for a clean test is anywhere from 100 to 200 on most GM vehicles but I don't know the exact figure for the 08 H2. Perhaps HummerZ or MIxmansc will know the exact mileage. Anyway, a good OBD2 testing tool can scan the condition and tell you if all the flags have been reset for you to do a re-test and pass.

 

Yes, that was what they did before the test. So I have driven over 500 miles since on freeway and city traffic road too. That O2 sensor kept staying on . Just wondering if this is a common problems on GM truck with the I2 sensor issues before we get it replace

 

You are not going to pass without completing a passing drive cycle, and if you have a code for a bad 02 sensor, that is going to need to be replaced first. Buy an AC Delco 02 sensor, as the cheap ones do not work as good.

 

Thank you

 

GM O2 sensors generally last about 100k or about 10 year, obviously this can vary depending on climate, fuel used,,, etc.

As long as an emission code is present the ecm will not reset to a normal condition that will allow you to pass.

Calif Phil's suggestion of replacing them with Genuine GM (AC/Delco) is a good one the originals lasted this long so you would be good to go for a long time before ever having to replace them again.