My engine light has come on orange, so i have taken it to a non MB garage in spain. He has hooked it up to a computer and stated that it is the DPS filter, i said replace it then, until he gave me a price of 3,500 euros????? to my horror. He said he will try using top grade diesel which may flush out the filter, can this work???? I have a 4 year old CLK 320 CDI Convertable!! Thank you!