Hi. I'm trying to fix a 2004 KJ with the 2.4L. I'm having an issue with the uptream O2 sensor reading and the car is driving very poorly/stalling easily when driving.

I'm getting an O2 signal of 1.27V when using a cheap scanner with the O2 connected. When I start the engine, 30 seconds later or so the voltage drops to around 1V.
I know the heater element in the O2 is bad since I'm getting no impedance with my multimeter and I've got a P0032. So I disconnected the O2 and still got 1.27V. This never changes.

Now, looking at the repair manuals I should be getting 5V with the sensor disconnected.
So I measured the O2 1/1 O2 signal (K41) harness pin and got 3.8V with the multimeter. Very odd. I then disconnected the C2 harness connector from the PCM and still got 3.8V from the PCM pin itself.

Please look at the attached pictures.

Note that the car has no secondary O2 sensor at all and it also reads 1.27V.

Any help is appreciated!


No O2 sensors. Getting 1.27V with the scanner.


Getting 3.8V from the 1/1 O2 signal harness pin.