O2 sensor error codes and what to fix

[_4_]

Long time lurker. What a treasure trove of information on this forum. Thanks to all who contribute!

I bought a 2000 Sahara 4.0 5 speed, and she runs great. I pulled the codes and here is what I’m getting


P0340 - no cam signal at pcm

P0135 - 1/1 O2 sensor

P0141 - 1/2 O2 sensor

P0155 - 2/1 O2 sensor

P0161 - 2/2 O2 sensor

P0158 - 2/2 O2 voltage short


Looks like I need all 4 new O2 sensors, but how should I go about fixing P0340 and P0158?

Also, how pressing are these fixes? Should they be done immediately or as time permits?

Lastly, should I replace the exhaust while I do the O2 sensors? It’s probably the original exhaust at 190k miles, and it does sound a bit loud. I’d like to return it to stock.

Thanks in advance!

 

[never monday]

P0340 and P0158 should be tracked down first.
I suspect the other 4 o2 sensor codes will heal when you fix 158

 

[Irun]

I've seen 02 sensors cause all kinds of whacky issues, so I'd probably flip what @never monday said. Start with known issues, i.e. the 02 sensors, and work from there. Just be sure to only use NTK/NGK 02 sensors when getting replacements!

 

[Irun]

As for the exhaust, if funds aren't a limiting factor, I'd replace it with that many miles on it.

 

[CharlesHS]

O2 Sensor voltage short; I would check for wires that have rubbed thru, burned thru OR possibly an internal short on O2 sensor 2-2.
Disconnect the pigtail on O2 sensor 2-2 to see if there is an internal short; if not... then examine the harness going to that sensor.
No Cam Sensor at PCM; I would check the three 32 pin harness connectors going to the PCM. Disconnect the harness connectors, check for oxidation and firmly reinsert into PCM receptacles.

 

[Winks42]

NGK #23122 - Bank 1, Sensor 1 (Upstream)
NGK #23506 - Bank 2, Sensor 1 (Upstream)
NGK #23099 - Bank 1, Sensor 2 (Downstream)
NGK #23099 - Bank 2, Sensor 2 (Downstream)

Here are the correct O2 Sensors If the problem is the sensor itself. But like others have said there might be a short in the wires and you should look for that first.

 

[glowell222]

NGK #23122 - Bank 1, Sensor 1 (Upstream)
NGK #23506 - Bank 2, Sensor 1 (Upstream)
NGK #23099 - Bank 1, Sensor 2 (Downstream)
NGK #23099 - Bank 2, Sensor 2 (Downstream)

Here are the correct O2 Sensors If the problem is the sensor itself. But like others have said there might be a short in the wires and you should look for that first.

Agreed, and near the exhaust manifold is a perfect place to begin.
For P0340, you should address soon, as this will very likely leave you stranded with a no-start situation.

 

[_4_]

Thanks for the responses everyone. I unplugged and clean all the PCM connections, and that took care of all of the codes except for:

P0135 - 1/1 O2 sensor
P0155 - 2/1 O2 sensor

Does that make any sense?

 

[_4_]

Also, any idea what this connects to?

 

[never monday]

View attachment 245292Also, any idea what this connects to?

Thats a ground wire

 

[glowell222]

View attachment 245292Also, any idea what this connects to?

That ground strap connects to the hood.