Sorry, my fault.
I read the first occurrence of the value, for a different mainboard.
Under mainboard 34 the pins are right.
I noticed that also the second thermistor and heated bed thermistor are enabled, so I tried disabling them.
When disabling all sensors, I got a MAXTEMP error, with a temperature going over 300 degrees celsius.
Then I enabled only the one I'm using, TEMP_0_PIN, and with all values (13, 14 & 15) it didn't work.
I'm kinda lost now...