[Sean P]

Hi all,

I own a 2017 Dodge Ram Laramie 2500 with 6.7 Cummins diesel.

I have had occasions where check engine light activates. When I take truck to Dodge dealership and the techs review codes, the common denominator is P0868 which is related to line pressure low.
On every occasion that I have gotten this code, the dealership uses the reader and line pressure is normal.
In March 2022, my local dealership installed a new line pressure sensor and in early October check engine light with P0868 code again.

Our truck runs great with no loss of power. The check engine light activates when I am pulling our fifth wheel trailer up a grade. On all check engine light activations , I have completed a good portion of a trip and then out of the blue comes the check engine light.

Today, I spoke to my local dealership Service Manager. He suggested I take the truck in so they can start a STAR case. As part of this case, the dealership reaches out to Chrysler Technical Services in an attempt to identify and resolve the problem.

Have any of you experienced the same issue?
If so, have you gotten the issue successfully resolved?

Thanks!

 

[FordCummins12V]

Well, if the truck is behaving and shifting just fine.... Wiring issue? I assume the trans fluid is at the correct level? How about the transmission temp, is that normal?

 

[Sean P]

Well, if the truck is behaving and shifting just fine.... Wiring issue? I assume the trans fluid is at the correct level? How about the transmission temp, is that normal?

Fluids and temps were normal

 

[FordCummins12V]

Well, since she's shifting okay and tests have revealed the PSI is good, I would next assume that wiring is a problem, or the new sensor is faulty (or possibly something in the ECU/TCM?) Pretty strange issue, nothing is worse than a seemingly stuck CEL.

 

[dsol]

I have had the exact same issue for years on my 2017 2500. Had it in to many dealers many times and they have thrown parts at it to no avail. Repairs have included sensors, filters and even valve body. It has only happened one time when I wasn’t towing my 15,000 lb fifth wheel and every other time I was towing.

Like you generally happens when the truck is warm and running fine. I will stop for fuel, accelerate to get back on a highway and I get the check engine light. If not for the chime and the light I would have no idea of the “problem” as the truck runs fine, all temps are normal and it doesn’t even have a harsh shift or shudder.

I started posting about this years ago and to make a long story short I now just live with it as it is not fixable by a dealer because they have no idea what is causing it.

As a new owner I was really concerned when this happened but 5 plus years later it doesn’t scare me any longer.

The reason it bugs me though is because I don’t want the illuminated CEL to mask another potential issue. However, because I have gauges and monitor everything obsessively when driving and especially towing I remind myself not to worry and after some time it will turn itself off.

My opinion is the parameter that triggers the low line pressure P0868 code is set too high for the low end. In other words, if the low pressure threshold was a few psi lower it would not trigger the fault.

I carry my code reader with me at all times and when the light comes on I check it the next time I stop to verify the code is only that and nothing else, then I just carry on. I don’t reset it any more because once I unhook and drive for a few days it turns off. The other reason I don’t reset it is because I want all the history in the code memory in case it does get worse and I need a real problem fixed and want the techs to see it.

I gather this is not that common of a problem because the dealers all scratch their heads and I don’t see many posts about it here in this forum.

The fact that you and I both tow heavy and probably heavier than most with the 68RFE leads me to believe the low line pressure parameter is not as factor for most but we are at the limit.

I wish I could get that low pressure parameter changed slightly because that would probably “fix” the issue.

 

[Sean P]

Hello,

Thank you for your responses.
Dsol…I appreciate your info. As you can understand this is a worrisome and frustrating situation. Thankfully, we have an extended warranty in the event of troubles. I will purchase a sensor and carry it with me on trips. Do you have a recommendation for a good sensor to purchase?

Thanks again everyone!
Sean

 

[dsol]

When you refer to sensor I think you mean code reader right? I picked up an OBD2 scan tool at Harbor Freight. They have a bunch and some have more features but all of them will read that code for you. Auto parts stores and likely Amazon will have them. Go with the most least expensive.


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[Lins]

Has the OP ever had the filters replaced?

 

[Sean P]

Lins…sorry but blanking on meaning of OP?

I did have transmission serviced April 2022.

 

[Lins]

Lins…sorry but blanking on meaning of OP?

I did have transmission serviced April 2022.

Original Poster- you. Did you have the code prior to the filters being changed?

 

[Jhenderson]

Both times I’ve experienced this code I’ve traced it back to chaffed wiring. The first time it was at one of the plugs behind the drivers fender liner. The second time it was where 2 harnesses overlap at the drivers side cab mount.

 

[Sean P]

JHenderson…thank you for responding. By chance, do you have pics of the areas where chaffed wires were found?
Again, thanks for your info!

Seán

 

[Jhenderson]

No pictures. Remove the drivers inner fender. You’ll find 3 plugs. 2 have a multitude of wires. Trace the wires from the plug on the side of the transmission to these plugs. You can even do a twist and tug on them to see if it causes the MIL. The other location will be obvious when you trace the wires. The 2 harnesses stack on one another at the body mount before going behind the inner fender. It only takes a small chafed spot to cause the problem so look carefully.

 

[dsol]

My initial check engine happened in the first few weeks of ownership so I doubt it was chafed wires in my case.

Plus, it has been to various dealerships many times over the years never to be figured out.

I guess anything is possible but given it happens in similar circumstances each time I think it likely mechanical.


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