S05 ENGINE HISSING - Alfa - 147 - eLearn

There is buzzing (low frequency noise) coming from the engine, whose intensity varies with the number of revs

1	CHECKING AIR INTAKE CIRCUIT	All OK	Problems met	Operation
		Results of the tests
	Check air intake system condition and seal	Continue to Step 2	Circuit component damaged	Replace the component involved
2	CHECKING ENGINE EXHAUST	All OK	Problems met	Operation
	Check the engine exhaust system and, in particular: manifold pipe exhaust silencer catalytic converter front/rear gaskets	Continue to Step 3	Pipe damaged	Replace the pipe
			Intermediate silencer damaged	Replace the intermediate silencer Op. 1076B26
			Rear silencer damaged	Replace the rear silencer Op. 1076B22
			Front gasket worn or damaged	Replace the front gasket Op. 1076B34
			Rear gasket worn or damaged	Replace the rear gasket
3	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present		Fault persists	Search for the fault starting from another symptom'