Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSSMART2009FORTWO BRABUS COUPE (451.333) L3-1.0L (132.930)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSKNOCK SENSORDESCRIPTION AND OPERATION
2009 Smart ForTwo BRABUS Coupe (451.333) L3-1.0L (132.930)
Knock Sensor: Description and Operation
2009 Smart ForTwo BRABUS Coupe (451.333) L3-1.0L (132.930)SECTION Description and Operation
GF07.04-P-6030MCC Component Description For The Knock Sensor
ENGINE 132.9 in MODEL 451.3 /4
A16 Knock sensor
Location
The knock sensor is located on the engine crankcase under the exhaust manifold.
Task
The knock detects vibrations which are emitted by the cylinders and transmits these in the form of an electrical signal to the ME-SFI [ME] control unit (N3/10).
In the event of failure of the knock sensor, the ignition performance map for low quality fuels or fuels with a low octane rating is used by the ME control unit.
Design
The knock sensor consists of:
^ A seismic mass
^ Piezoceramic perforated disc
^ Thrust sleeve
^ Housing
Function
The knock sensor is screwed through the thrust sleeve to the crankcase. The vibrations which are coming from the individual combustion chambers are transmitted by the seismic ground to the piezoceramic perforated disc. The piezoceramic generates an electrical voltage signal and passes this on to the ME-SFI [ME] control unit.
The piezoceramic consists of crystals on whose surface an electrical voltage is generated through deformation.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.