BiturboBoy_V2.0_S3--

cheap ($23ish) vs. expensive ($180-200). this we all know. Here is one question though.
The VW one is 3 wire one is 4 wire one. Question is this, when one splices the 1 wire of teh 3 wire sensor into the 2 wires on the S4 harness (onto the harness I assume), what are you losing? Is the S4's O2 sensor a redundant output sensor(2 outputs and one power, one ground i assume)? IF so, I guess all you lose is a little of the system's diagnostic capability of detecting whether or not the sensor is working. Anyone know for sure? Anyone have pics of the Sensors themselves or of the harness? TIA.

dscottjr

IIRC, the s4 has 2 grounds.

BiturboBoy_V2.0_S3--

what is the purpose of that i wonder. i wonder if one of the grounds is tied to case ground of the sensor (assuming some kind of case ground) housing? or is it really just 2 curcuit grounds.

dscottjr

ed at the diagrams and put a meter on the sensors but because of all the crap in my brain - i just can't remember. sorry.

BiturboBoy_V2.0_S3--

hmm....thanks anyway, hopefully someone will chime in with a diagram or soemthing.

JasonS4+Festicle

I thought the VW one was 4 wire also - I know the one I spliced had 4 wires.

dscottjr

<center><img src="http://pictureposter.audiworld.com/42392/etka_clips_-_o2_sensor_diag.jpg"></center><p>G108 and G39 are 02 sensors

NEPaNogaro

So the current of the heater does not create a voltage drop(increase actually) across the combined sensor/heater ground - creating a "bad signal".

Also might be so they can isolate noise by keeping the power and the analog sensor systems seperate.

Connecting them could be very bad - especially if they are using the 2 grounds to isolate noise - it could inject power noise into the analog ground plane.

BiturboBoy_V2.0_S3--

i searched the archives and seeemed to find some 3 wire talk. if they are both 4 wires...why the need to splice? why not plug and play?

funkadelic

the connectors are different..hence the need to splice. my VW o2 senors were 4-wire