Thinkdiag Sprinter J51 Fuel Tank Variant Coding Guide

Thinkdiag scan tools cannot only scan and reset codes but will allow you to perform variant coding…which is where you change the fuel/gauge programs. People have successfully used these tools to Install the J51 program in Mercedes Sprinters (J51 = Deactivate the Fuel Tank Algorithm).


Model example: NCV3 Sprinters (2006 – 2018)

You can use Thinkdiag or Thinkdiag2 to do coding.

Note on Android vs IPhone: The Thinkdiag app is available on both platforms but has limited functionality with the Iphone. On the Iphone changing Variant coding isn’t available. If you want to change variant codes (like the fuel programs) then that can only be done on the Android platform/App.


After you register the unit (Comes with a 1 year activation code) and update the firmware on the device through the phone app your ready to go. Let’s get into installing the J51 Code. 1st Turn your ignition key to the “On” position and click on the “All Systems Diagnostic button”.

Next click on “Vin Decoding”. The unit will locate your vin and verify the vehicle model and year your working with.

Next press “Automatically Search”.

Thinkdiag Sprinter Fuel Gauge Variant Coding 1

Next select your year range, i.e 2013 and up.

Select Diesel engine

Left hand steering.

Thinkdiag Sprinter Fuel Gauge Variant Coding 2

Select Automatic Transmission

Next click “System Selection”.

Now click “Information and Communication”

Thinkdiag Sprinter Fuel Gauge Variant Coding 3

Next is “Variant Coding”. This is where we we will find/change the Fuel Programs for the Level Gauge.

Then select “Instrument Cluster”

Select “Fuel Tank”

Thinkdiag Sprinter Fuel Gauge Variant Coding 4

We are after item number 3 here. We want the New Tank Algorithm to say Deactivated. Here we can see it’s Activated on the van. (J51 Fuel program = Deactivated on the New Tank Algorithm). Click on number 3.

Next Click Deactivated then scroll to the bottom of the page.

Click “OK” to accept Deactivated.

Thinkdiag Sprinter Fuel Gauge Variant Coding 5

Now we show “Deactivated” on number 3 but we haven’t written the change to the ECU yet. To save the changes to the van Click “Writing Code” in the lower left corner and follow next steps.

Press “Yes” to confirm that you want to write the change to the ECU.

Next turn the Ignition Switch to “Off” then press ok

Thinkdiag Sprinter Fuel Gauge Variant Coding 6

Turn the Ignition Switch back to “On” and press ok.

And your done, J51 Fuel Program is now installed!

Thinkdiag Sprinter Fuel Gauge Variant Coding 7



Thinkdiag will do fuel tank coding on NCV3 models. But failed to change the Fuel programing for the gauge cluster on VS30 2021 mode although there is a TON of Variant coding available.

So need to test by your own.


Read also:

Thinkdiag Mercedes Sprinter Variant Coding Review

How to Change Sprinter W906 Tire Size with Thinkdiag?

Vediamo Enable Hidden Mode Remaining Fuel in the Tank on Mercedes W212 W204 X204 W218