Withdrawal
Raise the car.
Using a screwdriver, loosen the cross-head clips securing the rear of the casing by ¼ turn -arrows- (under the engine oil pan) and remove the cover.
Loosen the fasteners on the front of the casing (behind the bumper) -arrows-, detach cover from bumper and remove.
Installation
Attach the front part of the casing first, then the back and fasten.
Lower the car.