2025 Cummins--Anyone notice that DEF gauge not reading correctly?

[Whauhunter]

2025 Ram 2500 Cummins---Anyone notice that DEF gauge not reading correctly on their 2025?
One time the gauge will read 3/4 a tank---then couple hours later shows 5/8 a tank---then it will read the same for several days. I don't really want to carry it into stealership and they flash it and mess up something else...... (because I can make do with it as it is)

I was doing a Google search of this very problem so I registered to the forum. Ya I’m having the very same problem with my 2025. When full It slowing works it way from full to 3/4 back to almost full then drops to 1/2 and will eventually go all the way to empty and cause the low def warning light to come on, the warning of 200 miles to limited power and if I either just keep driving it or stop and shut it off for 30 minutes and restart it it resets and goes back to full. Sometimes, the last two times, it has occurred in less than four miles of driving. I took it in to the dealer and they said they re-flashed it but it didn’t fix a thing. It did it again on my home from the dealer. The last 1/8 of a tank I watched the needle bump its way down into the red zone instead of just moving slowly. It seems to be associated with driving and road vibration as I let it idle for thirty minutes in the shop the gauge slowly worked its way back up to full. Taking it back to dealer again in two weeks.

 

[MacksRam]

I was doing a Google search of this very problem so I registered to the forum. Ya I’m having the very same problem with my 2025. When full It slowing works it way from full to 3/4 back to almost full then drops to 1/2 and will eventually go all the way to empty and cause the low def warning light to come on, the warning of 200 miles to limited power and if I either just keep driving it or stop and shut it off for 30 minutes and restart it it resets and goes back to full. Sometimes, the last two times, it has occurred in less than four miles of driving. I took it in to the dealer and they said they re-flashed it but it didn’t fix a thing. It did it again on my home from the dealer. The last 1/8 of a tank I watched the needle bump its way down into the red zone instead of just moving slowly. It seems to be associated with driving and road vibration as I let it idle for thirty minutes in the shop the gauge slowly worked its way back up to full. Taking it back to dealer again in two weeks.

Whauhunter,
Yes, sounds exactly like what mine is doing. Please let us know what you find out when you go back to dealer in two weeks. Thanks

 

[Whauhunter]

Whauhunter,
Yes, sounds exactly like what mine is doing. Please let us know what you find out when you go back to dealer in two weeks. Thanks

I will. I operate an auto repair shop out of my home but this truck is so new there isn’t any information on the truck, no info on any of the subscription services yet. Friday I had my wife sitting in it with it running and I was under wiggling the wire harnesses and connectors and banging on the def tank with a rubber mallet and nothing. It sat there idling for thirty minutes and the gauge slowing started moving back to full where it should have been.

 

[Whauhunter]

Whauhunter,
Yes, sounds exactly like what mine is doing. Please let us know what you find out when you go back to dealer in two weeks. Thanks

Well it’s been back to the dealer twice in the last three weeks for this problem. First time they “reflashed” the system and within five miles on my way back home it went to empty on a full def tank. Took it back this past Monday, the 18th, and dropped it off explaining again in full detail what it’s doing. Interestingly the gauge stayed on full the entire way there. They scanned it again and this time no fault codes. They agreed there is something wrong with the def pump/gauge sending unit. It’s all an integrated part. They ordered it, of course it’s on back order so the wait begins. Plus the gauge stayed on full the entire drive back to my home, 73 miles, but going into town 4 miles it acted up again halfway to town gradually moving toward empty but resetting after shutting it off and restarting it. The service writer said it’s good that it’s showing it’s on back order and not on a restricted parts list. We will see. I’ll keep you posted on this after I get the new part installed.

 

[MacksRam]

Well it’s been back to the dealer twice in the last three weeks for this problem. First time they “reflashed” the system and within five miles on my way back home it went to empty on a full def tank. Took it back this past Monday, the 18th, and dropped it off explaining again in full detail what it’s doing. Interestingly the gauge stayed on full the entire way there. They scanned it again and this time no fault codes. They agreed there is something wrong with the def pump/gauge sending unit. It’s all an integrated part. They ordered it, of course it’s on back order so the wait begins. Plus the gauge stayed on full the entire drive back to my home, 73 miles, but going into town 4 miles it acted up again halfway to town gradually moving toward empty but resetting after shutting it off and restarting it. The service writer said it’s good that it’s showing it’s on back order and not on a restricted parts list. We will see. I’ll keep you posted on this after I get the new part installed.

Whauhunter:
Thank you for the update. My truck DEF gauge is doing the EXACT SAME thing. I called my local dealer a couple days back to get an update on this issue--they state they still do not see a TSB on this issue and there is no need for me to bring it in. (I have carried it in once for this issue.) I am to call back in a few weeks to "see if they have an update". As you know when the gauge goes to empty (or near empty) if will flash "Speed limited to 5 MPH in 200mi Refill DEF"---The stealer (I mean dealer) told me that if I for sure have DEF in the tank---the truck will NOT go in limp mode---I don't know that I believe this. I think if the gauge reads empty and I have driven 200 miles---it will go into limp mode. Good news is---the gauge has not stayed on E very long--after driving a few miles or start/stopping the truck a couple times---it will go back to full....
Yes, please update after they install your new sending unit---based on my experience, that sounds like they are on the right track to the fix...

 

[Whauhunter]

Whauhunter:
Thank you for the update. My truck DEF gauge is doing the EXACT SAME thing. I called my local dealer a couple days back to get an update on this issue--they state they still do not see a TSB on this issue and there is no need for me to bring it in. (I have carried it in once for this issue.) I am to call back in a few weeks to "see if they have an update". As you know when the gauge goes to empty (or near empty) if will flash "Speed limited to 5 MPH in 200mi Refill DEF"---The stealer (I mean dealer) told me that if I for sure have DEF in the tank---the truck will NOT go in limp mode---I don't know that I believe this. I think if the gauge reads empty and I have driven 200 miles---it will go into limp mode. Good news is---the gauge has not stayed on E very long--after driving a few miles or start/stopping the truck a couple times---it will go back to full....
Yes, please update after they install your new sending unit---based on my experience, that sounds like they are on the right track to the fix...

Sounds like we’re having exactly the same problem. I brought mine in so it can be documented because if they can’t get it fixed by, I think, the fourth time then I can start the paperwork for lemon law. My Son did this on a 2023 Dodge gas engine pickup because the factory waited 39 days before they authorized a transmission for his first truck. By California law they have 30 days to either approve the repair or deny it. The original transmission had a cracked bellhousing they discovered in the process of replacing a leaking tail shaft seal. They ended up arbitrating a settlement of $7000.00. The seal began leaking again 1300 miles later so he took the $7000 and his 2023 truck and traded it in on a 2024 but a diesel this time. So far he’s had no problems.

 

[ddt4x4]

I just purchased a 2025 Bighorn and my Def Gauge just started reading low and I know it is full. After driving about five miles the gauge starting moving. When I shut it off and turn it on the gauge goes up. I thought maybe this happen because the truck is parked on an incline.

 

[Whauhunter]

I just purchased a 2025 Bighorn and my Def Gauge just started reading low and I know it is full. After driving about five miles the gauge starting moving. When I shut it off and turn it on the gauge goes up. I thought maybe this happen because the truck is parked on an incline.

Take it in and have it looked at and start the paper documentation trail. Mine is doing it more frequently now and will go to empty then the chime comes on and the warning of reduced power after 200 miles. If I shut it off for a few minutes and start it back up it goes back to the correct level. A couple of times I just kept driving it and it went back to the correct level.

 

[ddt4x4]

Take it in and have it looked at and start the paper documentation trail. Mine is doing it more frequently now and will go to empty then the chime comes on and the warning of reduced power after 200 miles. If I shut it off for a few minutes and start it back up it goes back to the correct level. A couple of times I just kept driving it and it went back to the correct level.

Thank you I will call them today.

 

[MacksRam]

Thank you I will call them today.

ddt4x4--what did the dealer say about the "floating" DEF gauge?

 

[Dirtstiff]

Have not read the whole thread.
Has anybody tried -
Hotshot DEFender DEF tank treatment

 

[ddt4x4]

ddt4x4--what did the dealer say about the "floating" DEF gauge?

Your timing is impeccable. It took me awhile to get off my butt, to call the dealer. I only have 1300 miles on my truck. Yesterday on the way to the dealer I video tape my DEF gauge. It was full and went to empty and at half before arriving to the dealer. The dealer is less than 3 miles from my house. They looked surprised about the problem. One of the service reps said this is not the first time he’s seen this problem.
They told me they found codes and the pump needs to be replaced. Then he was talking about the sensor. I asked ,“ was it the sensor or pump that is usually two different components”. He said they are the same device. Unfortunately the pump/sensor is on back order and they don’t know when it will be in. They will call me. The truck is safe to drive unless it gives me an alarm that says SEE DEALER then bring it in. Isn’t that what I just did? WTF I paid more money than I wanted for a truck that may not be operable. So I writing a letter to Ram and Knights Ram dealer. If I get alarm and it says see dealer does my truck sit there until they get the part?

 

[MacksRam]

Your timing is impeccable. It took me awhile to get off my butt, to call the dealer. I only have 1300 miles on my truck. Yesterday on the way to the dealer I video tape my DEF gauge. It was full and went to empty and at half before arriving to the dealer. The dealer is less than 3 miles from my house. They looked surprised about the problem. One of the service reps said this is not the first time he’s seen this problem.
They told me they found codes and the pump needs to be replaced. Then he was talking about the sensor. I asked ,“ was it the sensor or pump that is usually two different components”. He said they are the same device. Unfortunately the pump/sensor is on back order and they don’t know when it will be in. They will call me. The truck is safe to drive unless it gives me an alarm that says SEE DEALER then bring it in. Isn’t that what I just did? WTF I paid more money than I wanted for a truck that may not be operable. So I writing a letter to Ram and Knights Ram dealer. If I get alarm and it says see dealer does my truck sit there until they get the part?

ddt4x4,
Any more updates on your situation? Has dealer called you?

 

[ddt4x4]

ddt4x4,
Any more updates on your situation? Has dealer called you?

Ni, I was going to call them today. They told me I would be called when the part comes in. It’s frustrating purchasing a new vehicle and waiting on a part. I suspect they are on back order because they have issues across the USA.

 

[ddt4x4]

I was just reading online the pump and sensor are not together. The sensor is built into the tank and pump is separate. I called the dealer and they said my pump should be here by next Tuesday.

 

[HarryN]

I am wondering - how much of this is just from DEF tanks being kind of small and just sloshing ? Or just a loose wire connection / non perfect ground somewhere ?

 

[ddt4x4]

Ni, I was going to call them today. They told me I would be called when the part comes in. It’s frustrating purchasing a new vehicle and waiting on a part. I suspect they are on back order because they have issues across the USA.

I took my truck to the dealer on Tuesday. They replaced the DEF pump. It seems to fix the problem. I wasn’t happy that I gave them a full tank and they gave it back to me on a half tank. The 2025 RAM DEF tanks are 7 gallons.

 

[MacksRam]

I took my truck to the dealer on Tuesday. They replaced the DEF pump. It seems to fix the problem. I wasn’t happy that I gave them a full tank and they gave it back to me on a half tank. The 2025 RAM DEF tanks are 7 gallons.

ddt4x4,
Thanks for the info. I plan to schedule a service appointment at my local Ram dealer next week for this safety recall--see below.
While there I am going to have them look at my "floating DEF gauge" again---I am going to show them this thread about your fixed by replacing the DEF pump---can you post the DEF pump part description and part # here---that should have been listed on your repair receipt?? Thanks


December 18, 2025
FCA Recall #C3C
NHTSA Recall # 25C-882
Safety Defect/Non Compliance Description and Safety Risk

Some 2025 MY Ram 2500, Ram 3500, 3500 Cab Chassis, Ram 4500 Cab Chassis and Ram 5500 Cab Chassis vehicles may have been built with an Occupant Restraint Controller (ORC) module which may go into an offline state while driving. Federal Motor Vehicle Safety Standards (FMVSS) No.126 requires Electronic Stability Control (ESC) to be active while driving. An ORC module in an offline state may disable ESC. FMVSS No. 208 requires driver's airbag deployment during certain crash events. An ORC module in an offline state may not command airbag or pretensioner deployment in those crashes. Failure of the ORC module to command airbag and/or pretensioner deployment can increase the risk of injury in certain crashes. Failure of the ESC to function as designed can cause a vehicle crash without prior warning.
Repair Description

FCA US will conduct a voluntary safety recall to reflash the ORC module with updated software on all affected vehicles.
Recall Status

Incomplete but repair parts are available

 

[Lunnzz25]

Thanks for the add, sucks I had to join due to a potential issue with my truck, it is a 2025 which I purchased new. Yesterday I was sitting at a stop light that is at a decline and the nose was pointing down. I chalked it up to the DEF tank was at 1/2 tank, I shut the truck off and when I restarted it message was still there. I started to drive and maybe in less than a mile it went back up but was now under 1/2 tank. Of course being the weekend service dept at local dealership was closed. Going to call tomorrow and get it in for this issue and the recall for a software update. I will see what they say, truck has just under 5k miles.

 

[ddt4x4]

Thanks for the add, sucks I had to join due to a potential issue with my truck, it is a 2025 which I purchased new. Yesterday I was sitting at a stop light that is at a decline and the nose was pointing down. I chalked it up to the DEF tank was at 1/2 tank, I shut the truck off and when I restarted it message was still there. I started to drive and maybe in less than a mile it went back up but was now under 1/2 tank. Of course being the weekend service dept at local dealership was closed. Going to call tomorrow and get it in for this issue and the recall for a software update. I will see what they say, truck has just under 5k miles.

Tomorrow, I will scan my report for the dealer and post it on this thread. I park on an incline, but was told it should not matter. When this first happen to me I added four gallons of DEF. So I know the tank was full.