22 · Diagnostics

Engine hissing

Fault diagnosisEngine hissing

ENGINE HISSING

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 the condition and seal of the air supply circuit	Continue to Step 2	Circuit component damaged	Replace the component involved
2	ENGINE EXHAUST CHECK	All OK	Problems met	Operation
	Check the engine exhaust system and, in particular: Piping Exhaust silencers Catalytic converter gaskets	Continue to Step 3	Pipe damaged	Replace the pipe
			Rear silencer damaged	Replace the silencer Op. 1076B20
			Gasket worn or damaged	Replace the gasket
3	CHECK ON 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'

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