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02:35:52 - 05/06/2024
General Dakota Board
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pickemup
Gen III
 
11/13/2003
08:45:01
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 Subject: Oil in wire harness/O2 Sensor
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Message:
Hello,
I have been lurking in these forums for some time now and have learned some great stuff. I don’t know that I even qualify as a “Shade Tree Mechanic,” but I do as much of my own maintenance as possible, and fix things when I can.
I am now having a problem that is beyond my ability, and hope someone here can help. I also have learned something about Gen III Daks that I haven’t seen posted, so I hope I can help you all with a valuable heads up.
First the basics:
2000 Dakota Extended Cab 4X4
4.7 L V8
5 Sp
Stock
The truck has about 48,700 miles, and has had NO problems since new. It’s a New England commuter, so it doesn’t get abused.
It all started about two weeks ago when I changed the plugs for the first time. I put in Autolite 5224’s as widely recommended here. A couple of days later it stalled, and when restarted showed a Check Engine light. I pulled the code P0107, MAP Sensor. Thinking it had something to do with the plug replacement, I repeated the work I had done to make sure I didn’t inadvertently knocked something loose. I found that the passenger side cylinders were burning clean, but the driver’s side was very sooty indicating a way too rich mixture. Since the MAP sensor looks at the intake, which is shared by all cylinders, it made me think that the MAP sensor error was the result of the abnormal operation, not the cause.
I decide to check the driver’s side pre-cat 02 sensor, as it is the one feeding information to the computer for fuel mixture calculations. When I unhooked the O2 to engine harness connector I found oil in it. I cleaned the connectors and replaced the sensor with an aftermarket Bosch. Within about 20 miles of driving, the truck stalled and the code returned along with P0171.
Removing the O2 sensor, I again found oil in the connector. I have search the entire engine compartment area repeatedly, and find oil nowhere except on the INSIDE of the connector. I have repeatedly cleaned it, and it always returns. It appears to be flowing through the wires under the insulation, and has even found its way down into the splice housing on the new Bosch O2 sensor.
My dealer has been no help. Their computer says no reading on the O2 sensor and they insist the truck has to have a factory sensor. They replaced it and the replacement also filled with oil and died.
Here’s the part where I think I can help you all. I believe I have traced the oil back to a faulty pressure switch on the power steering pump! There was oil in that connector as well, and it looks and smells the same. When I brought this information back to my dealer, they admitted that they have seen the problem more than a few times.
I replaced the pressure switch ($18.00), and would recommend that you all consider this a regular maintenance item. Short money to avoid costly problems. The connector to the switch is now clean and dry, and the flow of oil to the O2 sensor connector appears to have slowed. It may take some time before it stops completely, now that the harness is full. My problem is that the engine is still showing P0171 and P0107 codes. After clearing the computer it takes 15-20 miles for the codes to reappear. The car sometimes hunts at idle, and occasionally stalls (always when decelerating), but otherwise runs o.k.. The drivers side cylinders are still running rich and the other side are fine. The exhaust smells bad as a result of the rich operation.
What should I be looking at next? The dealer has been no help. They are perfectly willing to just replace every part under the hood in the hopes of stumbling across the right one. Am I right in thinking this must be an exhaust rather than an intake problem? Could the oil have gotten into the O2 sensors themselves and ruined them. Has anyone used the Bosch replacements and found them acceptable? Could the above codes be the result of a bad cat? I see that there are a couple of TSB’s on 2000 Dak’s failing to properly diagnose catalyst problems, but don’t know the details.
Please help!
AR
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pickemup
Gen III
11/13/2003
14:43:54
| RE: Oil in wire harness/O2 Sensor
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Message:
Please note - This posting has been re-posted to the Open Forum section, under General Board
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Timberwolf
GenIII
3/19/2004
17:00:21
| RE: Oil in wire harness/O2 Sensor
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Message:
You're right, I had never heard of that before. As far as having to use "MOPAR" O2 sensors, that's all bunk. I have replaced both the front and rear in my truck with Bosch's from Autozone and haven't had a single problem. There are only a few manufacturers that make the sensors, and Bosch is the largest. Chances are they replaced them with exactly the same one and charged three times as much. I had a subaru that the dealer told me the same thing. $249 at the dealer, $69.99 at Autozone. What a scam. I have the 5.2, so I'm afraid I won't be much help on the cat question. I know the 4.7's have a different exhaust setup.
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DAHEMIKOTA
GenII
11/06/2004
00:47:51
| RE: Oil in wire harness/O2 Sensor
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Message:
Funny thing, when I worked at Chrysler Engineering, all the O-2 sensors,fuel injecters,fuel regulaters,fuel pumps were made by Bosch for Chrysler. Why would the dealer say that Bosch parts won't work When the Chrysler parts are Bosch with a Chrysler part number???????????? $$$$$$$$$$$$$$$$
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gjs4
GenIII
4/01/2007
22:57:03
| RE: Oil in wire harness/O2 Sensor
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Message:
The problem is the power steering pressure switch..it leaks oil into the connector/harness loom...cost me $2k to figure it out...fries sensors in no time..my delaer tried the same stuff by the way... trust me- this is the cure..
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