When I checked out the car at Goulburn I had a look at the air flow sensor and it is covered in oily dusty stuff, :20 I have a K&N air filter, so I can only gather the oil/dust is from that. I thought these filters WERE surposed to stop that. I cleaned and reoiled the filter about 16 months ago and done around 1500 klms in that time. Whats the best way to clean this sensor.