13: O2 Sensor Circuit

[Fidhle007]

I can't figure out how to get the voltmeter on the ECU contacts though, if I pull the back cover off the plug it just comes unplugged and creates a whole new set of codes...

[equate975]

Well you don't want power to it when your checking for continuity. So pull the battery cable off, unplug the ecu, and check from there.

[hoveringuy]

Let me know what you find. I have a similar problem... I get a "O2 heater" CEL occasionaly when I idle for a while. I've checked and replaced everything with no change.

[Fidhle007]

Well you don't want power to it when your checking for continuity. So pull the battery cable off, unplug the ecu, and check from there.

I thought you were saying to check for voltage with the engine running?

[equate975]

I thought you were saying to check for voltage with the engine running?

No, continuity. Put your voltmeter on ohms so that it beeps when you touch the 2 leads on it together.

Pull the ecu off and stick one lead in where the o2 signal goes. Then go to the o2 sensor and touch that wire.

If it beeps that means that the signal is going from a to b. Test each wire just to make sure everything is connected right.

You CANNOT have voltage on any of these wires or your going to blow your meter.

All of this will just 100% verify all the wires are going to the right place.

[Fidhle007]

Ok, that seems simple enough! Thanks!

[Fidhle007]

So after a month of ignoring the Check Engine light I finally get around to checking continuity. Pins 13 and 40 check out fine and neither seem to be grounded out but I don't have continuity from 87 on the O2 heater relay to pin 1 (I think) on the sensor plug. This obviously means I'm not getting any power to the heater but wouldn't this throw a more specific code? It should still be able to manage the car once everything is warm though and I'm not completely frying my motor, right?

Now it seems to me, the simplest fix has to be to just run a new wire straight from the relay plug to the sensor plug, right? I was going to go ahead and do this tonight but I chickened out as I have an AutoX tomorrow and didn't want to fry anything.