Hi. My 2012 Renault fluence 1.5 DCI started losing power especially when driving on inclined ways and hieghts. Few days after that and when it was time for regular maintenance, the air filter was found to be very contaminated and changed with a new one side by side with oil and oil filter changed. I was hoping that this would end the problem, but unfortunately the same problem exists. No light is turned on the dashboard. Any advices please. Thanks in advance