Moin. Did my girlfriend’s Smart 450 City Coupe (petrol, automatic) change coolant yesterday. Also ventilated at the back of the thermostat. Folded wonderfully. Today I wanted to drive him out of the garage and he makes a regular surren/rumbling at the back, like the attempt to insert the gear or so.. Always appear in rhythm.. to 3 bars in the display. Without running engine with only switched on ignition, it seems to be backwards and 1. gear insert. If the engine is running, it does not work. After some research, I hit on actuator etc. as a possible source of error. After a tip I often read a little bit further pushed to shock. It was vlt 2-3mm. No improvement unfortunately. I mean, that can also be rather improbably broken in the stand / worn out.. Cable breakage? Nässen while ventilating at the back of the thermostat? Has already come out well. Which cables exactly should I consider as suspects? Other ideas what that can be? I would be very gratefully ideas for error finding! Greeting Florow Florow.