Jump to content

3.0 Duramax DEF gauge fluctuates a lot.

jlong1984
 Share

Recommended Posts

jlong1984 Enthusiast

jlong1984

Posted
Posted

Is anybody else's DEF gauge all over the place? This morning it showed only two bars remaining but when I got back in the truck to drive home this afternoon it was 75% full. 

Rocz3cqg Enthusiast

Rocz3cqg

Posted
Posted

I have not noticed the fluctuations but the DEF gage as you probably know it is not a true level or flotation sensor. I believe and I say believe that the sensor only informs the ECM that the DEF tank is Full and the ECM calculates usage and sends the corresponding signal to the digital level indicator. I was down 1 bar in the DEF gage, I added 1 gallon of DEF and the gage did not move for 2 weeks / 300 miles to indicate full.  Did it take the sensor getting uncovered to tell the system the DEF tank was full?

newdude Senior Enthusiast

newdude

Posted
Posted (edited)

There is a delay in the DEF gauge which happens almost every time after filling the DEF tank.  Can take a few drive cycles to reset the level.  

 

From GM - Diesel Exhaust Fluid Consumption – TechLink (gm-techlink.com)

 

"Segmented DEF Level Gauge

The current 2020 Silverado 1500 and Sierra 1500 models have a DEF level gauge on the instrument cluster that provides drivers with a representation of how much DEF is in the DEF tank up. (Fig. 2) The DEF level gauge does not operate like a typical float-style gauge that is used in a fuel tank. The Engine Control Module (ECM) monitors the DEF level and consumption rate in order to calculate an estimated range. DEF levels are detected by the DEF level sensor.

 

There may be some fluctuation in the amount of DEF represented on the DEF level gauge. After filling the DEF tank, it may take a few key cycles to register the correct amount in the DEF tank. With the new segmented DEF level gauge, it is possible that after adding 5 gallons (18.9 L) of DEF that the gauge reads as a full tank after the fill event. However, if the actual level of DEF is just entering the last segment on the gauge, the gauge is likely to drop by one segment shortly after driving after the fill event. As a result, a driver could have an initial impression that the vehicle consumes an excessive amount of DEF."

Edited by newdude

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • Atlas
      Gas Prices

      By Atlas · Posted

      I don’t. The source is a far-right fake news site perpetuated by Glenn Beck. Funny how you clean up political posts and then regurgitate garbage from politically tainted sites. 
    • txab
      Gas Prices

      By txab · Posted

      Not a distraction. You miss the point of the article. It's not just for today's situation. Another way AI is being used and it may explain some of the prices changes when there is no apparent event to cause a 25 cent jump out of nowhere, only to immediately, the next day, begin to drop by 2 cents and so on. These situations were happening before the Iran thing fired off.   I used to be in the retail gas/service business. Pretty much a $1 increase in WTI would increase my price by maybe .10 cents. Now WTI can go down and retailers can get hit with a .35 cent increase out of nowhere.   I thought it was interesting read, since this is being used on all products we buy now
    • GMCustomerService
      2021 with Intermittent AC Cooling Issues

      By GMCustomerService · Posted

      We understand that intermittent AC concerns are inconvenient, @tjonesdfw, especially since they often do not show themselves when we want or need them to. We would like the opportunity to learn more about your experience with your Sierra and explore the best path of assistance moving forward. To begin, please visit: https://s.gmc.com/support-request  and fill out the support request form with all pertinent details. This form helps our team gather the right information and ensures your request is routed appropriately.
    • GMCustomerService
      P0700 & P0747 Dilemma )':

      By GMCustomerService · Posted

      We want you to have full confidence in your Silverado, @ceeemcgeee. Safety is our utmost priority, and we understand your concern after this experience. We would like to provide an added layer of assistance between you and your dealer as we pursue the resolutions of your transmission concerns. When you have a moment, we would like to learn more about your experience so we may explore the best path of assistance moving forward. Please visit: https://s.chevy.com/support-request and fill out the support request form with all pertinent details. This form helps our team gather the right information and ensures your request is routed appropriately.
    • BlueV8
      Disable AFM for $0: The M5 Method for 6-Speed Trucks

      By BlueV8 · Posted

      Disclosure: BlueV8 is a Supporting Vendor and sells plug-in AFM/DFM disablers.   Before you spend a dime with us — or with anyone — try the AFM disabler GM already built into your truck. It's the shifter, and it's free. ⏱ The 10-second version 🚫 Skip the M5 method if: Most of your miles are highway — M5 locks out 6th gear, so you cruise at higher RPM and burn more fuel You already know you'll forget — it only works if you do it every single drive Your lifters are already ticking — nothing that switches AFM off repairs existing damage You already run a tune or disabler — this would be doing the same job twice ✅ Worth trying if: You want AFM off today, for exactly $0 You want to test-drive V8-only life before buying anything Your driving is mostly town and short trips, where 6th gear barely matters Your truck is leased or under warranty and you won't touch the ECM — this is zero hardware, zero software 💡 The whole trick, in one paragraph Owners across GM forums keep reporting the same pattern: put the transmission in manual / range-select mode, pick M5 or lower, and AFM never activates — the truck stays in V8 the whole drive. Bump it up to M6 and V4 mode comes right back. Two of the cleaner threads on it are here and here. GM has never documented this behavior, so file it under "strong owner consensus," not gospel. The good news: it takes exactly one drive to verify on your own truck. Steps below. What "free" actually costs Effort, every drive. It's a routine, not a setting. Shift to M, tap up to 5, every time you get in. There is no set-and-forget here. 6th gear. When GM shipped trucks with AFM/DFM switched off during the 2021 chip shortage, its own estimate of the penalty was about 1 MPG — and those trucks kept every gear. In M5 you're also giving up overdrive, so expect the highway hit to be bigger than that. Patience. One Tahoe owner ran the L5 routine for two months, then got tired of it and bought a plug-in disabler — he had an extended warranty, so flashing a tune was off the table. That's not a knock on the method. That's just what month two feels like.   I put together the full instructions, limitations, and links to the original owner discussions here: https://www.bluev8.com/blogs/news/how-to-disable-afm-for-free-the-m5-method

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...