Oxygen sensor question

[GitEmSteveDave]

So I have been getting a variety of codes for one of my sensors: p0138, p0139 & p0141.

You must be registered for see images attach

Gonna order a NGK sensor off Amazon and ask the mechanic to replace the sensor next time I bring it in for whatever new problem it has, but my question is should I replace both sensors on that side at once?

 

[TahirTu]

I would recommend yes, and while you're at it might as well replace all four at once.
(and i happen to have my four still waiting for the next visit to the mechanic. haha)

 

[J33Pfan]

Yes, both at once. Think it;s in the manual too!

Did you check the O2 Relays and the wires going to the O2 sensor?

Also, it may not come out without taking the Cat out too. So order new gaskets, V Clamp, and Cat Bolts as well.

 

[GitEmSteveDave]

OK, had both bank 1 sensors replaced two days ago, but I'm still getting a pending p0141 error from that specific sensor. I'm gonna give it the weekend to see if it clears on it's own, but then gonna bring it back to the mechanic on Monday to sort it out.

If it was a relay, wouldn't more than one sensor be out, or does each O2 sensor have it's own relay? Since it started right after the engine was replaced, I was thinking that maybe when the new engine was put in, they squanched a wire. Would that be easy to test?

 

[Billwill]

Download the 2003 Jeep KJ Service Manual here.

Section 8W are the wiring Diagrams.
The Index of 8W has a Component Location section where you can search for Sensors Oxygen or sometimes Oxygen Sensors works...this directs you to the correct pages in the Wiring Diagrams.....looking for Bank 1 Sensor 2!

The relays are also shown....try swap them around.

You will need a cheap Digital Multimeter.
You need to check the wires going to the sensors from end to end for continuity then with all ends of that particular wire color disconnected...including splices check for any leakage to ground. The coonector to the PCM will need to be pulled off.Note that these wires go through Connector #C104 which may need re-plugging..the Component Index shows where the connectors are located and the plastic color.
If all ends are disconnected then that circuit should be hanging in mid-air so no leakage to ground should be showing.
If there is leakage then you need to physically trace the wires where possible to see if any insulation has been worn away so the internal copper is shorting to ground or to some other random wire.

Best way to measure wires from end to end where small pins in the connectors are concerned is to tape small needles or pins to the meter lead end so as to be able to reach into the small connectors or to pierce the insulation...make sure when measuring resistance to not touch the probe ends with your bare hands.

If you cannot physically see any damage but the wire has some continuity to ground you need to cut off all ends of that wire color and replace the wiring with new wires..I have done this about 13 times on my 2002 Export CRD!

I will have a closer look at the wiring diagrams and get back to you later.

www.colorado4wheel.com/manuals/Jeep/KJ/

 

[GitEmSteveDave]

Download the 2003 Jeep KJ Service Manual here.

Section 8W are the wiring Diagrams.
The Index of 8W has a Component Location section where you can search for Sensors Oxygen or sometimes Oxygen Sensors works...this directs you to the correct pages in the Wiring Diagrams.....looking for Bank 1 Sensor 2!

The relays are also shown....try swap them around.

You will need a cheap Digital Multimeter.
You need to check the wires going to the sensors from end to end for continuity then with all ends of that particular wire color disconnected...including splices check for any leakage to ground. The coonector to the PCM will need to be pulled off.Note that these wires go through Connector #C104 which may need re-plugging..the Component Index shows where the connectors are located and the plastic color.
If all ends are disconnected then that circuit should be hanging in mid-air so no leakage to ground should be showing.
If there is leakage then you need to physically trace the wires where possible to see if any insulation has been worn away so the internal copper is shorting to ground or to some other random wire.

Best way to measure wires from end to end where small pins in the connectors are concerned is to tape small needles or pins to the meter lead end so as to be able to reach into the small connectors or to pierce the insulation...make sure when measuring resistance to not touch the probe ends with your bare hands.

If you cannot physically see any damage but the wire has some continuity to ground you need to cut off all ends of that wire color and replace the wiring with new wires..I have done this about 13 times on my 2002 Export CRD!

I will have a closer look at the wiring diagrams and get back to you later.

www.colorado4wheel.com/manuals/Jeep/KJ/

Thanks. I swapped the relay I found for O2 Sensor Downstream:

You must be registered for see images

with the relay for the Wiper hi/low, so I'm gonna give it a few cycles to clear itself, and see if it's still in my pending list. If it's there Monday, I'm gonna bring it back to my mechanic, as he asked me to let him know if it was still throwin codes.