Moin Moin The Audi 80 Type 89 Bj,91 of my roommate has some problems He smokes out of the ventilation —–> Heat exchanger He doesn’t get really warm anymore —–> Probably the thermostat is defective Some things I don’t know anymore On the one hand, he jumps from time to time not too old on battery? Occasionally, the ABS indicator light lights up Then the car’s rear light almost went off wejl the speed is sucked off at once Who can help me?