see stop warning

friends partner 2.0 hdi 2004 model bumps, bumps in small bumps etc. a warning lamp called the minimum level of continuous cooling water and the stop light is on, it turns out when the speed increases, it turns off when it opens the bonnet and the sender in the water-antifreeze tank turns out, it turns on again and then turns off, what is this and how it gets better.

My brother could be from the customer, our vehicle was broken at some point in the car, I was looking at it on the way, I was looking at it, I was looking at it from the engine.

how is it dismantled