One possible reason is the fuel pipe which runsunderneaththe air filter box and developed a leak. When the engine vibrates, the plastic clips which hold the pipe in place tend to wear a tiny hole in the rigid part of the pipe and diesel sprays on to the rear of the engine.Another reason (and a much more serious one) is the injector seals need replacing.
Your heater core may have a leak in it, allowing the fumes to invade the inside of the vehicle.
You do not list the year. Unless you are talking about a Fiesta built in Europe that is fairly new, it does not have a Cabin Filter. The smell you are smelling is more than likely mold or mildew growing inside the vents. Very hard to remove. Search Google with the term "Odor from dash vents" for advice on how to remove it.
removel of door panal in ford fiesta 2002
it is inside the bell housing
broken oil seal? i had something simialr with my new Ford Fusion, turned out to be oil seal. I had some fumes coming in through the air wents inside as well , though.
Ford Fiesta was created in 2008.
Not all models of the compact Ford Fiesta have included a spare wheel and tire. However, recent models have featured inside mounted spare tires and wheels.
a ford fiesta 1.6
ford fiesta
replace ford fiesta clock
The 2012 Ford Fiesta has 16 valves.
Ford fiesta change the repenting belt