O2 sensors or PCM error - are these values correct?

[Alliance2000]

Hello everyone!

I bought a 2005 TJ Rubicon where the seller told me the CEL was on due to 4 cheap China O2 sensors - the error codes (he showed me via OBD): P0031, P0037, P0051, P0057.

I checked here on Wranglerforum and got 4 new O2 sensors from RockAuto:
- NTK 23158 (downstream, cyl. 4-6, bank 2 / sensor 2)
- NTK 23159 (downstream, cyl. 1-3, bank 1 / sensor 2)
- NTK 23160 (upstream, cyl. 4-6, bank 2 / sensor 1)
- NTK 23195 (upstream, cyl. 1-3, bank 1 / sensor 1) - this is the "newer" version of NTK 23018, the only one offered from RockAuto.
After installing them - still CEL with 3 of the 4 codes above: P0031, P0037, P0051 (read via VeePeak OBDCheck BLE+ with CarScanner App).

Today I checked all O2 wirings:
- All 4 sensor harness plugs have a common ground with good connections (G105 at lower right engine block - looks good and tight).
- All other 3 connectors of each 4 sensor harness plugs have good connections to the PCM connectors (harness side), no wrong grounds - so wiring should be good.

- When sensors are connected to the harness, the heater control pins have a connection to ground, all with 4.6 Ohm (Wrangler manual: 2-30 Ohm) - so heaters of the (new) O2 sensors should be good.

- PCM heater control connectors (at the PCM) have 3x about 75 kOhm against the PCM ground (C2 - pins 17 and 18, C3 - pin 17), and 1x about 6 MOhm (C2 - pin 18) - that’s the O2 heater control for O2 sensor 2/2 - this sensor doesn’t throw a code at the moment - would be P0057).

- With ignition on / engine off, all O2 sensors show 1.27V (Wrangler manual: 5V) - read via OBD. During engine idle, they show 0.04V - 0.06V and increase and decrease while driving (up to 0.9V).

- I swapped the ASD relay against the fog light relay (same spec), the fuse #17 (Power - 20 Amps) is also good.


Do you think that might be the PCM itself?

 

[JKP]

Yep.

@Wranglerfix

 

[Wranglerfix]

it is the pcm failing you. You will also get loss of gauges, usually the fuel gauge and stalling while driving. All of those are the result of Pcm failure.

 

[Gilaguy23]

Doesn't do you much good now but rule #1, Take what the seller says with a grain....er...big bag of salt when it comes to the CEL or easy fixes. There is s reason it was for sale. Im amazed at some of the BS stories Im hearing as I look for another jeep.

 

[Alliance2000]

Update:
I replaced the PCM with one from @Wranglerfix and CEL was off. Obviously the 4 emission tests were "not completed", but after 3 days of driving, finally the "O2 sensor" test switched to complete. Then after another day of driving, the CEL came on again and I got the codes:
- P0133 "Heated oxygen sensor (HO2S) 1, bank 1 - slow response" - confirmed
- P0431 "Warm up catalytic converter, bank 2 - efficiency below threshold" - confirmed

How come that even with a new PCM and 4 new NTK/NGK sensors, the P0133 error code shows up? And is the P0431 an indication of a failing catalytic converter, that just wasn't showing up due to the failing PCM before?

I also found the suction line that goes into the firewall to be fixed poorly, so I fixed it again with shrink tubing yesterday and cleared the codes. CEL is off (due to code clearing), but now I got another code "pending"
- P0457 "evaporative emission (EVAP) system - leak detected (filler cap loose / off)"

The fuel cap is not loose. This TJ is giving me headaches. Anyone some hints / ideas / helpful thoughts?

Edit: I did a video of the O2 sensors at idle - maybe that helps:

 

[JKP]

Check to see if the cat to exh manifold bolts are loose. A leak here will throw cat codes.