P0031 Puzzle
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JK Newbie
Joined: Dec 2023
Posts: 1
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From: Highland, MI
P0031 Puzzle
Hello all. I have a 2012 Jeep Wrangler 3.6L that I purchased for my son. It was in bad state of disrepair. I have since addressed all the mechanical issues and all DTCs with the exception of the P0031. For troubleshooting I did the following:
1/ Ohm'd out O2 sensor - 3.9 Ohms, in spec
2/ Checked resistance from heater control circuit to ground - Above 100 Ohms, in spec
3/ Checked heater control circuit open or high resistance by probing from sensor to PCM connector - 2.9 Ohms, in spec
4/ Checked wiring harness from sensor to firewall where it “disappeared” behind engine and not visible from below. No signs of chaffing, exposed wire or pinched wire. Wiring from PCM to firewall conduit still in good shape (didn't unwrap for inspection)
5/ checked grounds. Wires not frayed or loose in eyelet connectors. Put dielectric grease between connectors and attaching points
Loaded the parts cannon…..
6/ Replaced B1S1 02 sensor, knowing it may not be solution
7/ Read in another post that Engine coolant temperature sensor could be a contributing factor. Also from memory, there was at one point an engine temp related DTC that is no longer present. Replaced engine coolant sensor
8/ Sent PCM to aftermarket repair shop. They stated they fixed it and then swapped into one of their vehicle and drove 5 minutes without issue
9/Compared CAN data for voltage and 02 heater temp for B1S1 and B2S1. They track until P0031 is set, then B1S1 02 heater temperature changes to -83F and stays fixed.
9/ It seems DTC sets even at idle when engine gets to nominal operating temperature (~175F) Can only clear DTC if engine is cooled down
As far as driveability, the engine periodically seems to stutter, but not severly. Also has stalled twice for my son which is the main reason I want to fix or I would live with the DTC . Fuel economy about 17 MPG. Not sure if that is average or impacted by 02 issue.
Looking for advice, not sure where to go from here.
Thanks in advance for any recommendations.
1/ Ohm'd out O2 sensor - 3.9 Ohms, in spec
2/ Checked resistance from heater control circuit to ground - Above 100 Ohms, in spec
3/ Checked heater control circuit open or high resistance by probing from sensor to PCM connector - 2.9 Ohms, in spec
4/ Checked wiring harness from sensor to firewall where it “disappeared” behind engine and not visible from below. No signs of chaffing, exposed wire or pinched wire. Wiring from PCM to firewall conduit still in good shape (didn't unwrap for inspection)
5/ checked grounds. Wires not frayed or loose in eyelet connectors. Put dielectric grease between connectors and attaching points
Loaded the parts cannon…..
6/ Replaced B1S1 02 sensor, knowing it may not be solution
7/ Read in another post that Engine coolant temperature sensor could be a contributing factor. Also from memory, there was at one point an engine temp related DTC that is no longer present. Replaced engine coolant sensor
8/ Sent PCM to aftermarket repair shop. They stated they fixed it and then swapped into one of their vehicle and drove 5 minutes without issue
9/Compared CAN data for voltage and 02 heater temp for B1S1 and B2S1. They track until P0031 is set, then B1S1 02 heater temperature changes to -83F and stays fixed.
9/ It seems DTC sets even at idle when engine gets to nominal operating temperature (~175F) Can only clear DTC if engine is cooled down
As far as driveability, the engine periodically seems to stutter, but not severly. Also has stalled twice for my son which is the main reason I want to fix or I would live with the DTC . Fuel economy about 17 MPG. Not sure if that is average or impacted by 02 issue.
Looking for advice, not sure where to go from here.
Thanks in advance for any recommendations.
Super Moderator
Joined: Jan 2014
Posts: 2,109
Likes: 465
From: SE Pa. W. Chester County
Welcome to the forum. Your diagnostic efforts are very impressive and I have no additional suggestions.. BTW 17 MPG IMO would be good around Motor City.. Might be higher on the HWY at 55-60.
