Method for monitoring a display (43, 52) of a driver's cab (40, 50) of a transport means, comprising the steps of: - capturing a target process variable (S-PG) using a vehicle control device and producing an image presentation of a value of the target process variable (S-PG) using a display device (43, 52), - calculating an actual check code (I-PC) from pixel data of the image presentation of the value of the process variable, - ascertaining a prime number that is uniquely assigned to the calculated actual check code (I-PC) on the basis of a first table, wherein the first table is created in advance with the aid of the following steps: - producing an image presentation for a first value of a process variable, - calculating a check code in dependence on the image presentation, - uniquely assigning a prime number to the check code and storing the check code and the assigned prime number in the first table, - repeating the steps with each possible value of the process variable, - capturing a correct value of the target process variable (S-PG), which is produced by the vehicle control device and may deviate from the displayed value of the target process variable, - ascertaining a prime number product (PZ-P) that is uniquely assigned to the correct value of the target process variable (S-PG) on the basis of a second table, wherein the prime number product comprises the prime numbers of all the permissible actual check codes that are assigned to the correct value, wherein the second table was created previously with the aid of the following steps: - selecting a set of valid image presentations () for a first value of a process variable, - calculating a set of valid check codes () for the valid image presentations (), - reading the prime numbers () assigned to the respective check codes () from the first table, - producing a prime number product (PZ-P) by multiplying all found prime numbers () that are assigned to the first process value (W 1) and storing the first process value (W 1) together with the assigned prime number product (PZ-P) in the second table, - repeating the steps with each possible value of the process variable, - checking whether the image presentation is correct by ascertaining whether the prime number product (PZ-P) is divisible without remainder by the prime number that is assigned to the actual check code (I-PC). - capturing a target process variable (S-PG) using a vehicle control device and producing an image presentation of a value of the target process variable (S-PG) using a display device (43, 52), - calculating an actual check code (I-PC) from pixel data of the image presentation of the value of the process variable, - ascertaining a prime number that is uniquely assigned to the calculated actual check code (I-PC) on the basis of a first table, wherein the first table is created in advance with the aid of the following steps: - producing an image presentation for a first value of a process variable, - calculating a check code in dependence on the image presentation, - uniquely assigning a prime number to the check code and storing the check code and the assigned prime number in the first table, - repeating the steps with each possible value of the process variable, - capturing a correct value of the target process variable (S-PG), which is produced by the vehicle control device and may deviate from the displayed value of the target process variable, - ascertaining a prime number product (PZ-P) that is uniquely assigned to the correct value of the target process variable (S-PG) on the basis of a second table, wherein the prime number product comprises the prime numbers of all the permissible actual check codes that are assigned to the correct value, wherein the second table was created previously with the aid of the following steps: - selecting a set of valid image presentations () for a first value of a process variable, - calculating a set of valid check codes () for the valid image presentations (), - reading the prime numbers () assigned to the respective check codes () from the first table, - producing a prime number product (PZ-P) by multiplying all found prime numbers () that are assigned to the first process value (W 1) and storing the first process value (W 1) together with the assigned prime number product (PZ-P) in the second table, - repeating the steps with each possible value of the process variable, - checking whether the image presentation is correct by ascertaining whether the prime number product (PZ-P) is divisible without remainder by the prime number that is assigned to the actual check code (I-PC).