Hello together, I was recently with my Smart 451 in a free workshop. There was to be a large inspection according to manufacturer regulations. This included new oil, oil filter, air and pollen filter, new brake fluid, new spark plugs and the complete replacement of the coolant (every 4 years). I also had an error message from control unit: Lambdasonde, Bank 1, Sensor 1: voltage too high. The agreed price for the inspection was 250 EUR. When I picked up the car, I already saw in the checkbook that the replacement of the coolant was not checked. On my request, the boss said that the coolant was still “peak” and of such good quality, because it was changed directly in the smart center four years earlier and to the doll stuff that they tipped in there, one would even come as a normal workshop That’s why I would even worsen with a change in quality with it! But as compensation he installed particularly high-quality air and pollen filters for me! That seemed strange to me, but I left it at first, paid and drove home. That was exactly a week ago. Now I wanted to operate my windscreen washing system today and realized that the tank was empty. I also noticed that the door hinges of the passenger side continued to squeak. I then saw that the trailer of ATU was still attached to the container of the brake fluid from a year ago. That made me stubborn and I checked the brake fluid with a test device for its water content. The lamp lit yellow, < 1%. Since new brake fluid may contain the highest 0.05% water, the lamp should still be green after a week, if the brake fluid is still in use. I would be very interested to see how you see this story about the cooling fluid and whether it can actually be that after a week the lamp does not shine green when checking the water content in the brake fluid or whether it is rather the brake fluid of last July of ATU? Thank you in advance!