Posted by Michael Whitworth on April 15, 2007, 8:13 pm, in reply to "Oxygen sensor earth?"
Hi Phil,
I believe you ARE talking about a four wire sensor, If so Daves explanation above makes sense, apart from some of the sensors DO have a connection on the grey wire to the sensor body as well as returning back to ECU. I have read the reason for this but it has slipped my mind. The universal sensor will not have a connection on the grey wire to earth, which the ECU is looking for.