Proper O2 heater operation

[CarsSuck]

Basically, I seem to get no power to the oxygen sensor heater. Ive got power at the relay, tested the relay, it works, I get continuity where I should with pins 3 and 4 in the sensor connector.

I did find an air leak, the short hose that goes to the ICV. That hose never seems to last long before splitting. So that explains the goofy 900 rpm warm idle, but I'm still curious about the O2 sensor operation.

[Gregs///M]

The heater circuit should have 12V when the ignition is on. Check the Bentley manual, it has a great procedure to test the heater circuit and o2 sensor. The feedback should be 0.45 volts +/- 0.1 fluctuating. Its all in the manual.

[CarsSuck]

yeah, i have one and have learned not to trust it too much. There isnt even a diagram of that circuit in the book, i had to dig around online for the ETM.

So the questions stands, I have power to the relay, relay works (applied 12v and checked continuity across terminals, heard it click, etc), but no power at the 02 sensor connector. So I wonder what the real operation of the heater is, should it get power all the time or does it get a signal from the DME or what?

Doesn'e seem right, but I'm not sure what I can do about it since the wiring in the circuit checked out okay and there is 12v at the relay.