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Unread 11-07-2013, 09:28 PM   #1
veiri86
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2003 WJ 
 
Join Date: Jan 2013
Location: Tulkarem, Tulkarem, Palestine
Posts: 563
P0051 Oxygen Sensor help?!!

Hi guys,

Recently i bought another WJ, it is 03 Overland.

Am having the check engine light on it and the car idles rough. So I did the key trick and got P0051 which indicates short circuit in the oxygen sensor upstream of the cat at the passenger side. So before I start throwing money on a new sensor I would like to check my wiring harness to be sure it is not shorted, but unfortunately I don't have an access to the harness part which is behind the valve cover, so am thinking to unplug the harness from the O2 sensor and use my ohmmeter to check any short circuit, so any body can help me between which wires (which color) at the harness side shall I measure the resistance andl NOT to get 0.00 to be sure that my harness is not shorted.

I have the usual four O2 sensors set up

Thanks

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Build thread: [url]http://www.jeepforum.com/forum/f197/parallel-build-thread-2-x-wjs-1872002/[/url]

01' 4.7 Limited WJ 5" lifted, Rubicon Express 4.5" coil springs with IRO critical path setup and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), JKS HD tie rod (MOOG problem solver Ends), JKS HD drag link (Moog Probel solver Ends), 4.56 Yukon ring and pinion, Moog HD SSD107 Steering Stabilizer, IRO Front drive shaft conversion, Stillen slotted rotors all around with Stillen brake pads, IRO adjustable A-Arm, 3" all the way Kolak Exhaust with High flow Magnaflow Cat. Converter and Flowmaster Super 50 Muffler, 285/70R17 AT Kumho (33") on 17" BlackWheel rims 909B, K&N Cold air intake, Four nozzles Bosch injectors, and Flashpaq 3780.

03' 4.7 H.O WJ 3" lifted, OME HD with 0.5" Coil spacers and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), Moog Problem solver TRE's, IRO Front drive shaft conversion, IRO adjustable A-Arm, High flow magnaflow mini cats, high flow magnaflow cat, Flowmaster Super 44 muffler, 265/65R17 AT Yokohama on 17" Rays rims, and Flashpaq 3780
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Unread 11-08-2013, 01:26 AM   #2
andygio71
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Check out this PDF, it should have all of the wiring diagrams you'll need: http://wagoneers.com/WJ/tech/WIRING/wj-wiring.pdf
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Unread 11-08-2013, 03:19 AM   #3
veiri86
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Wj

Quote:
Originally Posted by andygio71 View Post
Check out this PDF, it should have all of the wiring diagrams you'll need: http://wagoneers.com/WJ/tech/WIRING/wj-wiring.pdf
Thanks a lot, am downloading it now and I will have a look at it.

Thanks again
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Build thread: [url]http://www.jeepforum.com/forum/f197/parallel-build-thread-2-x-wjs-1872002/[/url]

01' 4.7 Limited WJ 5" lifted, Rubicon Express 4.5" coil springs with IRO critical path setup and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), JKS HD tie rod (MOOG problem solver Ends), JKS HD drag link (Moog Probel solver Ends), 4.56 Yukon ring and pinion, Moog HD SSD107 Steering Stabilizer, IRO Front drive shaft conversion, Stillen slotted rotors all around with Stillen brake pads, IRO adjustable A-Arm, 3" all the way Kolak Exhaust with High flow Magnaflow Cat. Converter and Flowmaster Super 50 Muffler, 285/70R17 AT Kumho (33") on 17" BlackWheel rims 909B, K&N Cold air intake, Four nozzles Bosch injectors, and Flashpaq 3780.

03' 4.7 H.O WJ 3" lifted, OME HD with 0.5" Coil spacers and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), Moog Problem solver TRE's, IRO Front drive shaft conversion, IRO adjustable A-Arm, High flow magnaflow mini cats, high flow magnaflow cat, Flowmaster Super 44 muffler, 265/65R17 AT Yokohama on 17" Rays rims, and Flashpaq 3780
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Unread 11-08-2013, 05:38 AM   #4
Dealer24028
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here is the diagnostic flow chart for o2 sensor failures.
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Unread 11-08-2013, 09:33 AM   #5
rm2001wj
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See the attached pinout diagram for the connector. With the key OFF, a zero resistance between pins 1 and 2 (OR/DG and BR/WT wires) would indicate a short. With the key ON, and no short, the battery voltage will exist between those two pins (and wires).
o2-sensor.jpg  
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Unread 11-08-2013, 09:47 PM   #6
veiri86
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Quote:
Originally Posted by Dealer24028 View Post
here is the diagnostic flow chart for o2 sensor failures.
Sorry but seems I can't find the chart.

Quote:
Originally Posted by rm2001wj View Post
See the attached pinout diagram for the connector. With the key OFF, a zero resistance between pins 1 and 2 (OR/DG and BR/WT wires) would indicate a short. With the key ON, and no short, the battery voltage will exist between those two pins (and wires).
Believe it or not, I was waiting for your feedback as I saw your good responses about O2 issues here and on other forums, loool.

I measured the impedance between all of pins, and all of them measured 1 which means no short condition in the harness, on the other hand I measured the impedance at the O2 sensor terminal between all pins taking all the possibilities but all measured one, which means there is no continuity, so at this point am confused, both the harness and the O2 sensor showed no shorted condition but my code says the opposite, so shall I conclude that my O2 sensor is faulty and get new one from Kolak?
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Build thread: [url]http://www.jeepforum.com/forum/f197/parallel-build-thread-2-x-wjs-1872002/[/url]

01' 4.7 Limited WJ 5" lifted, Rubicon Express 4.5" coil springs with IRO critical path setup and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), JKS HD tie rod (MOOG problem solver Ends), JKS HD drag link (Moog Probel solver Ends), 4.56 Yukon ring and pinion, Moog HD SSD107 Steering Stabilizer, IRO Front drive shaft conversion, Stillen slotted rotors all around with Stillen brake pads, IRO adjustable A-Arm, 3" all the way Kolak Exhaust with High flow Magnaflow Cat. Converter and Flowmaster Super 50 Muffler, 285/70R17 AT Kumho (33") on 17" BlackWheel rims 909B, K&N Cold air intake, Four nozzles Bosch injectors, and Flashpaq 3780.

03' 4.7 H.O WJ 3" lifted, OME HD with 0.5" Coil spacers and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), Moog Problem solver TRE's, IRO Front drive shaft conversion, IRO adjustable A-Arm, High flow magnaflow mini cats, high flow magnaflow cat, Flowmaster Super 44 muffler, 265/65R17 AT Yokohama on 17" Rays rims, and Flashpaq 3780
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Unread 11-09-2013, 09:03 AM   #7
rm2001wj
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It is very probable that the heater in the O2 sensor does not short until it (and the sensor itself) gets hot. The usual fix for the P0051 is replacement of the O2 sensor.

If you want to play around with it a little more, you could first unplug the sensor, then erase the codes, and finally start the engine. This would definitely cause some O2 sensor codes, but probably not the P0051.
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Unread 11-21-2013, 09:08 PM   #8
veiri86
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Quote:
Originally Posted by rm2001wj View Post
It is very probable that the heater in the O2 sensor does not short until it (and the sensor itself) gets hot. The usual fix for the P0051 is replacement of the O2 sensor.

If you want to play around with it a little more, you could first unplug the sensor, then erase the codes, and finally start the engine. This would definitely cause some O2 sensor codes, but probably not the P0051.
So an update here.

You were right, and looks like my 4 O2 sensors are out. It is really rare to get all of them out together, but this WJ is new for me, bought it less than two months ago, so probably they were out one by one and the PO never changed any of them, so by the time I got the Jeep the 4 of them were out. I changed one of them only and now it idles much better, I changed the one upstream on the passenger side, but I was unlucky and got the one upstream on the driver side which has shorter wire, so I had to splice the new O2 sensor wire and extend it. I disconnected the battery after plugging the new O2 sensor to clear the codes, then put it back again and started up and drove it for 100 miles, so far so good and no check engine yet. The next three O2 sensors I will order the Denso ones which are exactly the same as the Mopar sensor, actually the Mopar sensor is Denso.

Then I have to check my cat. converter because usually they say the downstream O2 sensors indicate the life time of the cat. converter.
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R.I.P ratmonkey
Build thread: [url]http://www.jeepforum.com/forum/f197/parallel-build-thread-2-x-wjs-1872002/[/url]

01' 4.7 Limited WJ 5" lifted, Rubicon Express 4.5" coil springs with IRO critical path setup and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), JKS HD tie rod (MOOG problem solver Ends), JKS HD drag link (Moog Probel solver Ends), 4.56 Yukon ring and pinion, Moog HD SSD107 Steering Stabilizer, IRO Front drive shaft conversion, Stillen slotted rotors all around with Stillen brake pads, IRO adjustable A-Arm, 3" all the way Kolak Exhaust with High flow Magnaflow Cat. Converter and Flowmaster Super 50 Muffler, 285/70R17 AT Kumho (33") on 17" BlackWheel rims 909B, K&N Cold air intake, Four nozzles Bosch injectors, and Flashpaq 3780.

03' 4.7 H.O WJ 3" lifted, OME HD with 0.5" Coil spacers and Bilstien 5100 shocks all around, JKS adjustable Trackbar (KOR bushings), Moog Problem solver TRE's, IRO Front drive shaft conversion, IRO adjustable A-Arm, High flow magnaflow mini cats, high flow magnaflow cat, Flowmaster Super 44 muffler, 265/65R17 AT Yokohama on 17" Rays rims, and Flashpaq 3780
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Unread 08-07-2015, 03:59 PM   #9
2003jeepthing
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Wj WJ/4.0 only

I don't normally respond on forums however as a x-jeep dealer tech and multi jeep owner this may be of some help. Check the wire harness that sits on the cylinder head stud at the back of the engine near the firewall. The wire harness passes all the fuel injector wiring and the rear oxygen sensor (2-!) wiring from the PCM on the right side firewall to the left side of engine.. Engine movement and vibration causes harness chaffing thru the harness sheathing and insulation to short the wires to ground. This can be intermittent, occurring while moving but test okay with the hood up. ITS A JEEP THING...NO ONE ELSE WOULD UNDERSTAND !!
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Unread 08-07-2015, 07:06 PM   #10
car5car
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Your help is 2 years late.
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Unread 08-11-2015, 09:12 PM   #11
CarolinaWJ25
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Well thank god for it because I bet that is my problem as I was just messing around in that location a few weeks ago before this code arose.
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Unread 08-12-2015, 03:29 AM   #12
86cj74.2L
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For me I replaced the sensor fixed it.
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