Some of you might know, i have an ongoing battle against O2 sensors. I could never figure them out and they always go out on me.

I'm testing the O2 sensor with my DMM, i have the wiring diagram, i also know that the hot wire is yellow, the heated wire is green, the AF- is white AF+ is orange

testing it with the DMM in dc voltage it reads 3.228 average for both AF- and AF+

from what I remember a high voltage means rich reading, but that high? i seem to remember voltage for an O2 sensor is supposed to be .35 - .60

the wires aren't shorted anywhere, and even if they were they wouldn't read 3.8, they would read 14 or full voltage.

advice?

 

your AF runs 1-5 volts the O2 runs 0-1 volt.

 

so...primary reads 1-5 volt secondary reads 0-1?

wideband and narrowband right?

mine stays at 3.8

i have 3 sensors, none of which i'm 100% sure work, but they all read exactly the same

3.228

by logical standards that would mean that either none of them are broken, or all of them are broken.

 

what year is the car, and which ones have you changed? and have you done any exhaust or engine mods? b/c federal emissions is 8 years 80,000 mi.

 

It's an 07, no exhaust mods Or engine mods at the moment

 

So just out of warranty, that sucks, the chances that all three o2 sensors go out at the same time is slim to none. The fact that they all read the same voltage, and the voltage is 2x-3x the norm, makes me think its ECM related.

 

have you had a check engine light on for any of them andhow many miles do you have

 

yup, since i was turboed about 3 years ago lol

if it's ECM related it should read more than 3 volts.

that's what gets me, somethings getting a wrong reading and changing everything. i'm going to check again.