Moin together, on our Mercedes GL petroler the original installed Webasto heater Thermo Top V no longer reacts. (part number A1645001498) The fuses are in order and the Stardiagnosis (Mercedes program) only gives me this as error: Code 9000: The control unit A6n1 (control unit STH) is defective. Large cinema. 🙂 Since I have already had experience with the installation of 2 heaters in the past, I fixed the board / control unit of the heater. How can I test the part now, or is there a replacement for it? Are the control units of the Evo heater identical? P.s. Burned looks nothing on the board at first.