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

ddt4x4 said:
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.
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ddt4x4,
I have a service appointment scheduled at my local RAM dealer for Wednesday morning (01/07/26) for them to check my DEF gauge again. I had it at the dealer in Sept 2025--they did a software update at that time--it did not help anything-no improvement in DEF gauge function.
I told the Service Advisor that your fix was to replace the DEF pump--he said he was putting that in the notes for the technicians to see.... He said they will need to get it in the shop and on their machine--then reach out to their contacts at RAM. Hopefully they will REALLY fix it this time...
 
MacksRam said:
ddt4x4,
I have a service appointment scheduled at my local RAM dealer for Wednesday morning (01/07/26) for them to check my DEF gauge again. I had it at the dealer in Sept 2025--they did a software update at that time--it did not help anything-no improvement in DEF gauge function.
I told the Service Advisor that your fix was to replace the DEF pump--he said he was putting that in the notes for the technicians to see.... He said they will need to get it in the shop and on their machine--then reach out to their contacts at RAM. Hopefully they will REALLY fix it this time...
Click to expand...
Sorry so late to respond but the holidays took up my time. Yep got a call from the dealer and took it in on the 18th and they replaced the def tank gauge and pump module in the tank. It was on back order but they said they got one from another dealer. So far so good, it hasn’t acted up since. It’s interesting these parts are on back order when they still have the parts to keep building them. Anyway hope they get yours fixed for you. Also I was able back on Black Friday to purchase a couple of newer bydirectional scan tools that have the software to connect the AutoAuth website so I can unlock the secure gateway module and be able to scan my truck for codes and by directional communication.
 
Whauhunter said:
Sorry so late to respond but the holidays took up my time. Yep got a call from the dealer and took it in on the 18th and they replaced the def tank gauge and pump module in the tank. It was on back order but they said they got one from another dealer. So far so good, it hasn’t acted up since. It’s interesting these parts are on back order when they still have the parts to keep building them. Anyway hope they get yours fixed for you. Also I was able back on Black Friday to purchase a couple of newer bydirectional scan tools that have the software to connect the AutoAuth website so I can unlock the secure gateway module and be able to scan my truck for codes and by directional communication.
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Whauhunter,
Thanks for the info---I will inform my Ram Dealer Service Advisor in the morning of the parts they replaced to get your working correctly--this may or may not be of benefit to them.
What is the main purpose/advantage of this bydirectional scan tool? This is new to me....
 
Well I will be taking mine in tomorrow for a recall and will inform them of the issues with my DEF gauge. I dropped to empty this morning and gave me the warning with a 3/4 full tank. I will let them know about the fix that has been working so far for Whauhunter and see what they say. I am not going to get excited I have not been impressed with our local dealerships.
 
Quick update:
I carried the truck to my Ram dealer Wednesday morning--in an effort to fix erratic DEF gauge. They found a TSB on the issue--Rapid Response Transmittal (RRT-25-093)--this TSB called for them to reflash the ECM. This did NOT fix it--before I got home the gauge started floating from Full tank, back to 3/4, down to 5/8 and back to Full. I called them back--I am to carry back in, and they are going to connect truck to their machine and open a Ram STAR case--said I will probably need to leave it 2-3 days. He "confirmed" it would NOT be a situation to where I would have to leave the truck longer.. He said they will probably have to install a new DEF pump, but Ram required them to do the TSB flash first.
 
I bought my 2025 DRW 1 ton last March. It was delivered with full 7.5 gal of DEF. I didn’t plan to drive it much until I got the truck camper to go with it. My concern was crystallization as it sat over time. 1 year “warranty” by boxed DEF maufacturers. https://www.rvtravel.com/ask-dave-def-shelf-life-and-how-long-it-lasts-in-the-tank-rvdt-1887/

FYI:
1. Yesterday, at 4134 miles, I got the, “50mph reduction of speed in 200 miles” notification. My DEF gauge now included a red highlighting where the ‘E’ is. And the DEF low idiot light illuminated. Looks like a hurricane warning. The entire usage of this truck so far has been unloaded.
2. Hot Shot recently come out with a product to mitigate crystallization of DEF. I bought a bottle. Pretty cheap so if it doesn’t work, not much loss.
Hope this helps someone.
 
2025 2500 Prospector XL Rebel. Built July 2025. 3000 miles same DEF gauge issue. Dealer is replacing tank under warranty.
 
TK42ONE said:
2025 2500 Prospector XL Rebel. Built July 2025. 3000 miles same DEF gauge issue. Dealer is replacing tank under warranty.
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TK42ONE,
Is the dealer replacing the entire DEF tank with all its components OR the DEF pump itself?
(the only reason I ask is because I am still working with my dealer to get the issue resolved)
 
MacksRam said:
TK42ONE,
Is the dealer replacing the entire DEF tank with all its components OR the DEF pump itself?
(the only reason I ask is because I am still working with my dealer to get the issue resolved)
Click to expand...
They are replacing the whole tank they said.
 
MacksRam said:
Quick update:
I carried the truck to my Ram dealer Wednesday morning--in an effort to fix erratic DEF gauge. They found a TSB on the issue--Rapid Response Transmittal (RRT-25-093)--this TSB called for them to reflash the ECM. This did NOT fix it--before I got home the gauge started floating from Full tank, back to 3/4, down to 5/8 and back to Full. I called them back--I am to carry back in, and they are going to connect truck to their machine and open a Ram STAR case--said I will probably need to leave it 2-3 days. He "confirmed" it would NOT be a situation to where I would have to leave the truck longer.. He said they will probably have to install a new DEF pump, but Ram required them to do the TSB flash first.
Click to expand...
With out looking at my paperwork the dealership did the same Rapid Response on 9 Jan and truck is still having DEF gauge issues and I currently have 5200 miles on the truck. And just the other day the message popped back up. But yesterday the message went out by itself and has not come back on and I currently have just over 1/2 tank of DEF. And after doing an oil change (yes I know really early) and fuel filter change I get a CEL for low fuel pressure I did cycle the ignition 7-8 times. I used Fleet Guard Filters From Geno's just like the OEM ones and yesterday that CEL went out on its own.
 
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