Low Voltage at 02 Sensor Wire Harness

I have a 2004 Vauxhall (Opel) Corsa. I am an American living in Britain.

My Check Engine Light recently illuminated. I have codes P0130, P0135, and P0560.

P0130 = O2 Sensor Circuit Malfunction (Bank 1, Sensor 1).
P0135 = Oxygen O2 Sensor Heater Circuit Malfunction
P0560 = System Voltage Malfunction

I just had both the pre-catalytic converter 02 and post-catalytic converter 02 sensors replaced. My car has two, four-wire 02 sensors. One is on the exhaust manifold; the other on the exhaust pipe.

Anyway, the same codes came up after replacing both 02 sensors. I discovered that I am receiving low voltage at the 02 sensor at the exhaust manifold. The heater wires are receiving about 8.6 volts with my ignition turned on (one is grounded). I measured at the wire harness for the exhaust manifold 02 sensor.

I don’t see corrosion, frayed wires, ripped wires, cut wires, etc., anywhere in the car.

Quite frustrated!

Any ideas?

Disconnect the negative battery terminal and reconnect after an hour. .Sometimes, it will reset the computer and erase the codes.

I did that. But the codes came back after driving a short time/distance.

Measure voltage for O2 sensor at ECM. If voltage is right there, you have bad wire or bad ground.

I am just blue skying by commenting without knowing the schematic for your car. If it were my car I would be looking for a relay that the ECM turns ON. These heaters draw a lot of current that the ECM would usually not handle so look there.

Thanks for the advice. The problem is I don’t know how to measure the ECM voltage. It’s confusing! I did take the ECM out and clean it with electrical contact cleaner. I did not see any corrosion on the ECM (i.e. green terminal pins). Tracing the wiring is difficult. My car has dozens (or more) wires.

Re: I did check the relay for the ECM. It was fine. Might check, again.

The hardest part in checking ECM outputs is finding the proper diagrams. With some research you can find them.You also need to know what your probing. If you are uncomfortable about doing this you may want to find someone with some electrical experience to help

Exactly how are you measuring that 8.6 volts at the oxygen sensor heater circuit . . . ?

Here’s what I would do . . . with ignition on and everything plugged in properly, backprobe the heater circuit positive side directly at the sensor and hook up the meter negative lead directly to the battery negative post

If you’ve got 12V, you know the problem lies on the ground side of the sensor heater circuit