To calibrate a tank for a fuel level sensor (FLS), follow the steps below.

- Empty the fuel tank. Make sure the car battery is charged and won't die during the calibration.
- If the FLS is not installed yet, install it according to the manual.
- Configure the tracker in such a way that the data is saved at least once every 10 seconds while you are calibrating the tank.
Prepare a table with two columns: X and Y. In the Y column, you should indicate the amount of fuel in the tank, and in the X column, the corresponding voltage value. To find out this value, request data messages from the unit in the Wialon monitoring system and find the value of the FLS parameter (this parameter is different for different trackers).

We don't recommend using a voltmeter to determine the X value due to the voltage drop in the circuit and the accuracy difference between the voltmeter and the tracker.

If you are using a digital FLS, you can take the values for the X column from the configurator (a special application for fuel level sensors).

The table should contain as many rows as you conditionally divide the tank into parts, as well as an additional row corresponding to a volume of 0 litres.

- Write down the start time of the calibration. You can also write down the time of adding each part of fuel to find the corresponding messages in Wialon easily.
- In the X column of the first table row, specify the voltage value before adding the fuel. Enter 0 in the Y column of this row.
- Divide the entire volume of the tank into 10-20 parts.
- Pour a part of fuel. In the Y column, enter the resulting fuel volume in litres. Wait 2-3 minutes until the fuel level in the tank becomes even and the tracker records a few more messages.
- Repeat the previous step until you fill the entire tank.
- In Wialon, take several messages generated 2-3 minutes after adding each part of the fuel. In these messages, find the parameter with the voltage value from the FLS, calculate the average voltage value for each such group and enter it in the X column.

Next, follow the instructions for filling out the calculation table in Wialon.

See the examples of configuring a calculation table for an FLS here.