Rerouted Oxygen Sensor Wires, PCM is Throwing a P0132 Code

[cloves]

Hi everyone,

This isn't an easy post but I am going to try to condense it as much as possible. Recently my 2000 4.7 durango power steering pressure switch failed and it started to pump power steering fluid into my harness (common issue). The fluid got as far as my upstream oxygen sensor and fouled it up.

Rather then reusing the wires at the connector (x4), I decided to just rerun 3 of 4 new wires to the PCM seeing as it seemed like an easy task. I got the wiring schematics, and then ran a new wire to the sensor signal, pcm ground, and common ground (its the ground for the heater wire) up near the pcm main harness (using the same 18 gauge wires). The last wire which is the 15 amp fused heater wire I just reconnected seeing that it was not fouled.

I connected the o2 sensor signal wire by cutting it and butt spliced with the pcm's wire. For the 2 grounds I just used a crimp connector.

I then picked up a bosch universal sensor and plugged it in. After running the car for a few, the pcm is giving me a p0132 "1/1 O2 Sensor Shorted To Voltage": Oxygen sensor input voltage maintained above normal operating range.

Considering I ran all new wires I was wondering if anyone had any insight as to what the problem could be? One Dodge tech suggested getting the OEM sensor which is by Denso, but I have already cut into the harness so it doesn't make much sense imo unless the sensor from bosch is not as high quality.

Thanks for taking the time to read this, any insight would greatly be appreciated

 

[MikeHalloran]

Disable anti-theft on the radio.
Disable the airbags.
Disconnect the battery.
Pull the ECU.
Use an ohmmeter to look for the short in the harness.

If it's really not there, get the OEM sensor.





Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

To late now, but why did you not just clean the original harness with solvent then soapy water then dry off with air.

Regards
Pat
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[cloves]

Fluid was pumped into the center of the wire, it really wasn't going to get cleaned anytime soon. Plus I didn't want to short my new sensor.

Dodge also says to bypass the original in a TSB.

 

[patprimmer]

Umm

You have me somewhat confused. Wire used in electrical harness is a metal core coated with plastic that shrinks onto the metal and seal. If the battery is disconnected first, or the appropriate fuse removed or the ignition turned off (maybe), how can you get a short if there is no power supply.

Anyway, to late now, the loom has been cut and patched.



Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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[cloves]

The wire that was contaminated was a common ground. A common ground that was shared by the o2 sensor. The power steering pressure switch failed and pumped at who knows how psi fluid slowly but steadily into the wire. If you examine a copper wire its composed of many strands of copper wire. Needless to say it happened, yes its hard to believe but its common issue on these dodge vehicles.

 

[bill190]

If you still have your old oxygen sensor, connect a multimeter on low DC volts to it and to the metal on the sensor screw in part or other wire if two wire.

Then heat it with a torch and you will see that it makes electricity when it gets hot!

But not 12 volts.

Then measure your new sensor wire to ground with a multimeter. When the engine is cold, there will be no voltage. As it heats up inside the exhaust, it will start to generate voltage.

If it starts out with 12 volts, then something is fishy!

Another thing you can try is to remove the negative battery terminal for about 30 minutes. This will clear out the engine computer memory and it will then "relearn" its engine settings. Drive it above 45 mph to give it a bit of "relearning".

 

[WGJ]

O2 sensors generally generate very little current, so I wonder whther there is an issue with the 'crimped' earths being too resistive.


Bill

 

[patprimmer]

With no real evidence, I suspect the quality of the patch to the loom and still suspect that more than a clean was necessary as oil between the strands really does no harm so long as the ends of the strands have very good contact with the fitting where it is crimped or preferably soldered.

Are you sure all repairs have perfect clean metal to clean metal contact. One way to ensure this at the bolt to the chassis end is to use a star washer between the fitting and the body or chassis rather than between the bolt head anf the terminal. This cuts through paint and corrosion to ensure a contact.

Regards
Pat
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[MacGyverS2000]

With no real evidence, I suspect the quality of the patch to the loom and still suspect that more than a clean was necessary as oil between the strands really does no harm so long as the ends of the strands have very good contact with the fitting where it is crimped or preferably soldered.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Thecardoc]

Cloves...

First, always use the correct sensor, not one that claims to be a universal fit. Second crimp connectors and such are not made for the precision repairs that are demanded by the computer controls on today's cars.

Start by looking in service information at the code set criteria, and especially the code description.

P0132 HO2S B1S1 is high O2 sensor voltage on sensor 1, bank 1. If you grab a scan tool and look at the voltage being reported by the sensor at key on, you should see a 5v. That's because the sensor is not turned on, and the PCM supplies a 5v reference. Once the sensors heater circuit warms the sensor sufficiently, it will pull that 5v reference down to what ever the voltage the sensor should be producing,which would be based on the contents of the exhaust gasses in the pipe/manifold around it. The possible reasons for that voltage remaining high are that the sensor circuit is open so the PCM only see's it's own Vref. The heater circuit ground is open, which first of all allows for a back feed, as well as not allow the heater to turn on. A loss of the 12v power to the sensor heater circuit, and/or the sensor improperly connected. (A problem avoided first hand by installing the correct sensor.)

Quote"
Disable anti-theft on the radio.
Disable the airbags.
Disconnect the battery.
Pull the ECU.
Use an ohmmeter to look for the short in the harness."Quote

How many hours should someone pay for diagnostics at this level Mike? An ohmmeter is the last tool that should be used for analyzing this issue, no scratch that. An Ohmmeter has absolutely no value to a technician when diagnosing a problem like this. Checking continuity of, or to a circuit should never have been assumed to mean that an ohmmeter was the tool that was going to be required. Professional automotive technicians, especially ones working at a dealership, under warranty, are expected to diagnose this problem in about 18 minutes (.3/hr). Any longer than that, and they are working for free. This problem would take an experienced technician less than ten minutes to diagnose.


Pat...
The correct repair should have been to simply replace the O2 sensor with the correct one, and solder in a new, correct pigtail for it. Then go back to the PCM and inspect it for fluid intrusion. Sad to say, but if the power steering fluid penetrated the PCM's connector, The PCM will need to be replaced. Purists will argue that, but they aren't the ones who will have to step up to the plate and pay for the part out of their own pocket if it comes to that in order to take care of the customer if they happen to get it wrong. If power steering fluid made it to the PCM, along with replacing it, the O2 wires affected must also be cut and jumpers spliced in so that any other fluid still inside the harness cannot work it's way through and into the new PCM. Even the companies that rebuild the PCMs simply throw the board in the trash if they find fluid contamination.

 

[patprimmer]

Cardoc

I see your back for a while at least.

Good to see you maintaining your equilibrium by having a chip on each shoulder.

Cloves has not logged on since the 25th of June, so I doubt he will get much value from your unbillable hours you just so kindly donated, but we stupid engineers might be learn something.

Also I doubt he was to worried about the hourly rate as he was working on his own car.

If by attacking professional engineers made you feel better, your post was not completely wasted.



Regards
Pat
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[cloves]

Hi all, still checking the thread

I ended up using an ohm meter to make sure I had continuatity. I also ended up picking up the OEM Denso sensor. Hooked up all the wires again and everything was back to normal.

 

[patprimmer]

So the universal sensor was not universal

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[cloves]

The ecm did not like the Bosch universal sensor. Odd thing is another person used the bosch universal with success according to a post on the web.

 

[thruthefence]

I'm no expert on Electronic fuel injection, but it seems every system I've laid eyes on, kept all the engine sensor grounds on a common stud, which itself is grounded back to the engine case or frame by a large robust jumper.

unless I read it wrong, the ground on the "heater wire" terminated at the same ground. Is it possible that heater control is somehow integrated into the ecu?

 

[Thecardoc]

Thru. Many of today's systems to control emi (noise) use bussed grounds inside the PCM. That way if some type of EMI is induced into the sensor, it moves the ground voltage level as well, and allows the PCM to see the correct sensor output.

Cloves, nice to see that you did see my input, when I responded to your post I saw it was a few weeks old and had not revealed a conclusion. Plus seeing what responses that you had gotten, it was obvious that you had not been given a clear direction about how to proceed. Plus if someone else in the future searched this, and was fighting a similar issue, IMO it would not have armed them with all of the information they might need to guide them to a conclusion. Thanks to your feedback now they will have that.

Pat.
Feel free to ignore any of my posts should I decide to continue. Looks like I'm not the only one with a chip on his shoulder.

 

[cloves]

The o2 sensor on the durango has 4 wires. 1 is the heater wire. 1 is a common chasis ground. 1 is an ecm ground which is a "low noise" ground. 1 is the sensor wire.

The heater wire just supplies voltage to the o2 sensor so it heats up quickly. In previous years the cats would heat up the o2. The voltage gets the car into closed loop faster then using the cats.

 

[thruthefence]

DUH.......when I read "heater ground" I segued off into "defrost the windows & keep your feet warm" territory.

In the words of Emily Latella, "nevermind".