Replacing control board of water heater - need to adjust integrated sensor, but lack tool to do so

Question

I finally received the control board for my water heater. Upon reading the instruction manual I found the following note:

"When replacing the control board the size of the container of the water heater and the integrated sensor offset eventually needs to be adapted. For this procedure you need the customer service plug."

From reading other material I know that the integrated sensor is a temperature sensor.

I already contacted the customer service, which states that they do not provide support for repair parts. Because I lack the customer service plug I wanted to ask what the worst is that can happen if no adjustments of container size and/or integrated sensor offset are made.

Edit:

Model:

AEG DEM 80 Comfort EL Variowall
Eno: 234192
F-No 1809-500066

Answer 1

After a lot of reading I came up with a partial answer, namely if adjustment to the temperature offset are necessary. I'm not an expert so if it is incorrect please point it out

The integral sensor is a temperature sensor which spans the height of the water heaters interior. It is the component 2 in the drawing below.

If you look at the interior of a water heater. ([Source])2

Now because the integral sensor spans the whole height of the interior of the water heater and because warm water rises water at the top of the water heater will reach the desired temperature sooner than water at the middle or bottom. However because the sensor measures the temperature along the whole interior height the heating will stop only after the temperature measured over the whole interior reaches the desired temperature.

This means that the temperature at the top of the water heater can temporarily reach higher temperature than desired. This overshooting can cause a shutdown of the security mechanism of the water heater.

This however depends if the desired temperature is set close to the maximum temperature. For example with my water heater the maximum temperature is 95°C and the temperature set is 60-65°C. So overshooting is unlikely to cause a shutdown.