loup05

ok so i took my car to get a smog test and it failed. the guy told me that it gives out to much corbon monoxie or something like that. he said its most likely the oxygen sensor that has to be replaced. can anyone help me with this what does the sensor run for. the guy said around 120

Duane_in_Japan

We need the gas readings please, is your guy allowed to test and fix also, some shops cannot. He needs to look at the O2 sensor voltage on a scope or scanner, tell us where it is. Tell him to force it to go lean and to go rich if he knows how, if not go elswhere, tell us all the dirty details so we can save you money on an O2 sensor. Be sure what is failing CO or something else, CO is a lean / rich indicator. Too much CO, too rich, O2 stuck high 0.8V range, create a nice vacuum leak and the voltage should come down or rev up the engine for a bit and then decellerate, this will create a lean condition and the voltage should come down around 0.2V.

This is a sticky subject so need lots of info.

loup05

i dont know anyof that but I'll go with the guy and find out so u guys can help me more. My brother in law said its because my "check engine" light is on. he said that once we turn off the check engine light it will pass the test. I highly doubt this but wat do u think Duane?