ground on a 3 wire O2 sensor ????
 

Probably a stupid question but am I correct ????

on a 3 wire O2 sensor (wire-1) heater ; (wire-2) signal ; (wire-3) common ground for heater and signal.

The reason I ask is does a 3 wire use the exhaust system as the ground for the signal to the DME.

If so, is there any ground spot for the exhaust.


Thanks again


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1984/85 944na
Kalahari Beige (gold) exterior / Black interior
Los Angeles / San Diego
Lookin for ideas etc...
http://www.carquip.com/parts/graphix/944.jpg

the one wire is the O2 sig. Block is ground.
The other 2 wires are for the heater only.
It doesnt matter which is power or which is ground.

A 3-wire sensor uses chassis ground through the exhaust system.

On your car there should be a rectangular two-wire "bullet" connector with one male, and one female "pole" somewhere in the vacinity of the O2 sensor signal connector. This connector is for the heater wires on the sensor.