Here in Mexico again. Cousin’s 1999 Yukon, 5.7 V8, imported from California. The transfer paperwork said 105,000 miles so I am guessing it has 120,000 or more on it.
It recently failed smog verification, and the smog booth told them it had a bad sensor. They did not say which one, except the “gas sensor”.
The problem is, it has 4 sensors, as best as I can tell. Two before cat converters, and two after. Sensors cost even more in Mexico than in the US, and I wanted to be sure if possible before buying sensors. And, at this time I am not even sure the sensors are bad. So, if I can come up with no better information, he may be forking out a weeks pay as a wild guess…
I took my Equus 3140 scanner, with live data and hooked it up. No driving, just started motor and started reading live data while it warmed up. Everything seemed to be correct, though I think I will look at it again tomorrow to see if maybe I missed anything, such as all readiness.
No codes found. I got the green light.
I did record all live data, but think putting them all here would be excessive. Temps looked correct. I noticed it said AIR OFF.
STFT B1 -2.3%
LTFT B1 -6.2%
STFT B2 -3.1%
LTFT B2 -3.1%
O2s B1 S1 (v) bounced around ended up .840
O2s B1 S2 (v) .755
O2s B2 S1 (v) .805
O2s B2 S2 (v) .735
Live sensor test:
O2S B1 S1 0.480 no spec listed
O2S B1 S2 NO TEST
O2S B2 S1 0.480 no spec listed
O2S B2 S2 NO TEST
My 2002 Toyota Sienna California heated sensors have totally different values. Like 3.4.
LOOKS LIKE ONE NON CONTINUOUS FAILED!
Non continuous test
Test ID $07
Component ID $0C
Test Value (HIGH) $dc00
Tests $0C; $03; $06 in spec. Only $07 fails. As you may suspect I have no idea what it is testing.
I have Googled until I almost fell off my chair, and can find no explanation for GM non-continuous tests, except pay boards.
The best I could come up with was a PDF file which said non-continuous tests tended to usually include: Evap; EGR; Catalytic Converter; Air; and O2 Sensor, though it implied some cars may have more. Clearly, some of these could cause a smog test fail.
I do not want to run EVAP test because it says I must see the service manual to see how to stop it. Sigh.
Thanks for any tips or help on this.
AFTERTHOUGHT: I think tomorrow I will go back, and assuming it has a PCV valve, check that sucker. I don’t think they are heavy on maintenance, though I have got them to changing transmission fluid and antifreeze.