Actually I found it very easy after taking the time to read into the program and playing for an hour or two.
Just nobody else was able to read this technical american english
The control light for different sensors did not work, or did never turn off.
I took the time to get into the details of the program and found the errors, then I made several changes first on the laptop, downloaded to the car computer, updated, turned off to activate, uploaded for a check up, and when it all was done, the control lights were working exactly as they were supposed to, lighting up when exceeding the maximum temperature of an individual cylinder or low oil pressure at a certain rpm, or whatever else may be wrong. There are "just" a few dozen sensors... and numerous possibilities of functions - and malfunctions.
Then he asked if it is possible to have the oil light working like on a regular car, so it lights up when turning on the power switch, but turning off when starting the car, and ... by then such a minor change I was able to do in a minute.
On the other car were even more lights not working - or "on" at all the time - so that guy just "disabled" the installed programm to keep the car running... now his is fixed and happy also.
... so when I grow up I will become a genius
just kidding. maybe it was just luck.