I have just collected my 2014 Astra SRI, 1.6 Diesel from the garage as the engine management light was on and car had gone into limp home mode. The diagnostic check revealed that the MAP sensor was working at 2% when it should have been 20%. The sensor was replaced and all seems well. When I collected the car the mechanic showed me the old sensor and in particular the amount of black residue on the filter attached to the sensor. There may be a problem down the line with the Turbo being clogged with the same residue and I'm keen to avoid this. My question is, is there anything I can put into the engine to clean this residue??