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Rear O2 sensors has steady volts, is that normal???
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Roland Jacques Offline
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Rear O2 sensors has steady volts, is that normal???
Rear/post O2 sensors has steady volts ???
I need some input on O2 sensors. and EFIE

I'm working on my GMC 2001 3500 Savanna Van.

I was checking the MAF & O2 sensors for determining what EFIE and MAF handler i should get, and making sure the Sensors did not need to be replaced.

The O2 front sensors seems to be acting correctly.
***But the rear O2s I'm not sure what they are suppose to be reading or doing? The rears both read 330 mv and don't fluctuate. Is that normal?

I would add that my Cats are gone, and I don't get any codes.


Not sure about the MAF, ether its a Hz or a volts MAF It has three wires.
At idle
red = 13 volts
yellow= 4.4 volts And 2.400 - 2.500 Hz
black = Ground?
09-15-2010 05:10 AM
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mike Offline
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RE: Rear O2 sensors has steady volts, is that normal???
Those rear sensors sound like they're probably bad. Without a cat, they should definitely be moving around. You can see what the voltages should look like by watching the video that's at the end of the Section 1 in these installation instructions: http://www.fuelsaver-mpg.com/doc/EfieIns...gital.html

As for your MAF, it sounds like voltage type, but I can't really tell. If you can watch that voltage as you start the car, you should see it make some very large change as it goes from no flow up to startup, and then dropping back down into an idle. The voltages will be proportionate to the flow of air going through. If it's not, but just stays and 2.4 to 2.5 volts the whole time, you likely have a frequency type. The really only true test is to put a meter on it that has a frequency function.

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09-15-2010 08:32 AM
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Roland Jacques Offline
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RE: Rear O2 sensors has steady volts, is that normal???
Thanks

Typo
The yellow wire measured 2.400 to 2.500 "k" hz ( i left the K out) i guess i should have just reved it up and watched the Hz if they move or not.
09-15-2010 03:45 PM
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