Multiple O2 Sensor Codes, Sensors Already Replaced

mtnsoccerguy

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Hey everyone. I'm new to this forum and am trying to help my friend get his 2005 3.7L Liberty running. The car should be CA emissions since it has been in state since new.

Story Time:
Car has been sitting since 2014. We put a rebuilt short block in because the previous block had cracked. Car runs well except it throws codes very soon after being started. Codes have been reset and come back very quickly. Maybe 15 miles of driving have happened.

P0131
Oxygen Sensor Circuit Low Voltage (B1S1)
P0132
O2 Sensor Circuit High (B1S1)
P0151
O2 Sensor Circuit Low (B2S1)
P0152
O2 Sensor Circuit High (B2S1)

All four codes will set and keep the MIL illuminated. Reading live data from a scanner shows me that the sensor readings do indeed peg high and low for long enough to trip the codes but they also have periods where they appear to be reading normally. They tend to peg high and low in sync with each other. The original sensors were replaced with NTK sensors and then MOPAR sensors with no change in indication.

I have no clue what to make of the indications. The wiring I can see appears to be intact although I have no broken apart the loom to see what is going on inside. There was a mouse living in the engine compartment, but we vacuumed his corpse out. I can not find any chewed wires though.

I can not think of anything that would explain these symptoms besides a weirdly failed PCM. I recognize that I don't know everything though so hopefully you guys can let me know if I have missed something obvious or if there are some tests I can run. Thanks in advance for the help.
 

LibertyTC

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Do a full re-set of the codes by removing both battery terminals, isolated away form battery, & tape or clamp cables together for 45 minutes.
Then re-attach them & start the Jeep up, any difference then?
 

mtnsoccerguy

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Do a full re-set of the codes by removing both battery terminals, isolated away form battery, & tape or clamp cables together for 45 minutes.
Then re-attach them & start the Jeep up, any difference then?
P0132 and P0152 (the high codes) both set again while P0131 and P0151 are pending. I suspect with a little longer runtime they will also set.
 

LibertyTC

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Sorry to hear that.
It then points towards electrical issues & potentially the 02 sensor pigtails need to be tested for voltage requirements.
Hopefully 1 of our members are more familiar with that process.
 

mtnsoccerguy

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Just an update.

Took a better look at the wiring near the PCM and found the culprit. The mouse did get some chewing in. Front O2 sensors seem fine now. Getting a P0420 code, but that is a different can of worms.
 

Ksat

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Thanks for keeping us updated.
 

Jeremy6305

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Hey everyone. I'm new to this forum and am trying to help my friend get his 2005 3.7L Liberty running. The car should be CA emissions since it has been in state since new.

Story Time:
Car has been sitting since 2014. We put a rebuilt short block in because the previous block had cracked. Car runs well except it throws codes very soon after being started. Codes have been reset and come back very quickly. Maybe 15 miles of driving have happened.

P0131
Oxygen Sensor Circuit Low Voltage (B1S1)
P0132
O2 Sensor Circuit High (B1S1)
P0151
O2 Sensor Circuit Low (B2S1)
P0152
O2 Sensor Circuit High (B2S1)

All four codes will set and keep the MIL illuminated. Reading live data from a scanner shows me that the sensor readings do indeed peg high and low for long enough to trip the codes but they also have periods where they appear to be reading normally. They tend to peg high and low in sync with each other. The original sensors were replaced with NTK sensors and then MOPAR sensors with no change in indication.

I have no clue what to make of the indications. The wiring I can see appears to be intact although I have no broken apart the loom to see what is going on inside. There was a mouse living in the engine compartment, but we vacuumed his corpse out. I can not find any chewed wires though.

I can not think of anything that would explain these symptoms besides a weirdly failed PCM. I recognize that I don't know everything though so hopefully you guys can let me know if I have missed something obvious or if there are some tests I can run. Thanks in advance for the help.
Had the same problem due to bad cats causing them to get to hot. Changed the cats and was able to reuse the O2's. No codes now runs great.
 
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