Another PO138 code thread.. and again it wasn't the O2 sensor

[Huerito]

96 4.0 XJ 2WD OBDII

So I can't pass smog until I clear this code. I replaced the O2 sensor, it was old anyways.. and the CEL came back on. I have ran a search and it seems that other 96 XJ owners with the same code have also found out their O2 sensor is ok.

I don't have the 96 FSM and since this XJ is OBDII, I cannot rely on the key on-off trick to read codes. I just finished fixing a blinker problem on this car, (faulty relay), and I still have to fix the horn and cig lighter that don't work.

My question is, since the O2 sensor was not the culprit, and I have a high voltage code.. could the blinker, horn, cig lighter and O2 sensor problems be in some way related? I am wondering if the problem might be somewhere in the relay center under the dash. That is where the blinker issue was... and I think this is where the voltage regulator for the O2 is.. I don't know. Can anyone chime in? If you have a 96 FSM, could you PM me please? I wanna get this done during this holiday days off.

[Huerito]

Bump..


if anyone has the schematics for the O2 sensor.. could you please PM me.

[Kejtar]

Originally Posted by Huerito

96 4.0 XJ 2WD OBDII

So I can't pass smog until I clear this code. I replaced the O2 sensor, it was old anyways.. and the CEL came back on. I have ran a search and it seems that other 96 XJ owners with the same code have also found out their O2 sensor is ok.

I don't have the 96 FSM and since this XJ is OBDII, I cannot rely on the key on-off trick to read codes. I just finished fixing a blinker problem on this car, (faulty relay), and I still have to fix the horn and cig lighter that don't work.

My question is, since the O2 sensor was not the culprit, and I have a high voltage code.. could the blinker, horn, cig lighter and O2 sensor problems be in some way related? I am wondering if the problem might be somewhere in the relay center under the dash. That is where the blinker issue was... and I think this is where the voltage regulator for the O2 is.. I don't know. Can anyone chime in? If you have a 96 FSM, could you PM me please? I wanna get this done during this holiday days off.

did you check the OTHER o2 sensor? With a 96 and OBDII you will have two O2 sensors

[langer1]

PO138 is o2 voltage high (Bank1 sensor2) did you replace the correct one?
There is (Bank1 Sensor1) and (Bank1 Sensor3) also.

[Huerito]

Yeah, that one is after the catalyc converter. I replaced that one.

The car passes emissions, "bank one sensor one" is the sensor before the cat that sends info for air/fuel adjustments. When this one goes out, you won't pass emissions.

[langer1]

Originally Posted by Huerito

Yeah, that one is after the catalyc converter. I replaced that one.

The car passes emissions, "bank one sensor one" is the sensor before the cat that sends info for air/fuel adjustments. When this one goes out, you won't pass emissions.

I thought a 96 had 3 pre-cat sensors.

[Huerito]

There are only two. One upstream and the downstream.