White smoke Mercedes Diesel

Hi everyone. The problem is that for a while now my car has been emitting white-gray smoke from the exhaust pipe. It's not very thick, but it's quite unusual. I'm worried because I don't know if it will pass the MOT/vehicle inspection... what could be wrong with it? And how much would it cost approximately to fix?

If that smoke is water vapor, then it's the head gasket, but for that to be possible the water level in the reservoir needs to drop considerably. The black smoke is fuel; an injector might be leaking, and it's expensive, haha, in Chile around 400,000 pesos.

It may be that too much diesel is passing through or that the diesel pump pistons are a little worn; you should have the entire injection system checked.

Oil to the pistons may pass, because, the turbo is being abolished or it may also be that the vents of the valves have been screwed.