Hi. I purchased a 2005 3.5L 2WD Pacifica. It is throwing P0132 and P0138 check codes. I have replaced both fore and aft O2 sensors with OEM Mopar parts and am still have these check codes after disconnecting battery and clearing the codes with my ODBII scan tool. The code are thrown about 30 seconds from starting the vehicle. I have allowed the engine to run for 30 minutes and cleared the codes ... and still receive these codes.

My scan tool can graph data. Both O2 senors are showing a steady 1.270V reading with zero variance. Using the same scan tool I checked two other vehicles and I see O2 sensor variance ... so the tool is good.

Using a multi-meter I have ensured both O2 sensors have a good ground and I cleaned the ground point on the body of the vehicle.

I am pretty certain the next steps are:
1) Trace both O2 sensors wiring to the PCM and look for an open or short.
2) If not a wiring issue, replace the PCM.

Does this sound correct? Am I missing anything?

Thanks!

 

Are the O2 sensors MoPar, or aftermarket?
Besides the fact that the aftermarket parts industry has gone to hell, some O2 sensors, like Bosch have problems on MoPars, because they do not meet the vehicles requirements, even when the manufacturer of the part says it will work.
I started buying only factory parts with my old Dodge Intrepid, when it blew thru several after market sensors in just a few months, and 2 aftermarket radiators, that both failed a few months after they were installed.
The factory parts, including the radiator, have lasted for years now, and the car is still running strong.
Even something as simple as a spark plug from Bosch has failed quickly in my old Intrepid. The book said they would work, but a couple months after I installed them, they started to fail.

 

BiliTheAxe. You bet. I went with Chrysler parts from the Dealer $209 for both).

The odd thing is the exact same reading on both O2 sensors using my TOPDON ODBII graphing diagnostic tool. I am showing 1.270v on both sensors in live data and I have taken a direct multi-meter read at both heaters and they are showing something like 1.2 ~ 1.3v with key-on and car not running. I know the 1.2 voltage on my tool is not the heater voltage ... and I have heard the O2 sensor heaters run at 6 VDC. I am thinking the heater circuits have to have a load before I can take a correct read.

Anyway, there are no other issues (that I can tell) with the vehicle...and this Pacifica has a ton of bells and whistles. I have a wire tracing tool arriving today from Amazon. I am thinking the only two things left to do is 1) check the wiring for opens or shorts, and then 2) grab a rebuild/re manufactured PCM.

The sad thing is ... my girl wants me to get rid of this thing and I am having fun with it. I do not feel right selling someone a car knowing it has a problem (even if they know it has a problem).

 

Yeah, it is likely in the wiring that you will find the problem.
Have you done any work in the engine bay? If so, that should be the first area to look for damaged or pinched wiring, and also near the exhaust manifolds, since it would be easy for O2 sensor wires to ground out there..
As for your girl wanting you to get rid of it.
My ex wanted me to get rid of a dog I had, a beagle.
She pestered me about it, til I finally agreed, and got rid of the dog, and a month later, my ex left after I had gotten rid of the dog.
Just keep that in mind.

 

Have a 2005 3.5L 2WD Pacifica (the Guppy!) that I love and is driving great w/ over 300k miles on the clock. Gave up throwing good money to chase down the engine codes a few years ago. Drive my Pac with the engine light on. (my wife puts up with my Pac, she does all her hating on my old pickup truck).
Annually when the TX state emissions/safety inspection comes due, I reset the Monitors, use my scanner to watch as they all come up, leaving the "bad" monitor not set, slide into the inspection station and get my inspection done. Texas allows a vehicle to pass emissions test, allowing one Monitor to not be set.
Just a workaround idea I thought I would throw out there..

 

Hey...how do you leave the "bad" monitor not set? I have a 2018 Topdon (Chinese) scanner tool and I can reset emissions codes. But I have no idea how to shut down the monitor.

Many thanks!

 

This weekend I bypassed the stock wiring from the PCM to the pair of brand new Mopar O2 sensors. My reader live data is showing zero variation in O2 sensor readings (both still flat lined at 1.270v). So, at this point, I have replaced the PCM, O2 sensors and wiring. I triple checked the wiring and everything is good.

Now, I can run the Pacifica for 30 minutes with no check code. Then turn off the engine and restart. After which I receive P0132 and P0138 within 30 seconds. I can clear the codes and repeat these results.

All I can think now is I am having an O2 sensor heater issue. Maybe some undocumented voltage feed specifically for the PCM that drives the heaters. Other than that...I am at a total loss now.

 

Who wants this phucking Pacifica for free? I am sick of it.

 

If you are near new Jersey, I would take it. Have you checked the wire harness for damage? That close to the exhaust, it is not uncommon for wires to get burned.

Read thru this. It may help.
https://www.obd-codes.com/forums/viewtopic.php?t=14151