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Home >> Audi >> 2001 >> S4 Quattro, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Computerized Engine Controls >> Input Devices >> Engine Speed Sensor
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Engine Speed Sensor

Engine Speed Sensor (RPM) sensor is an inductive pick-up, located on the left side of engine block by the flywheel. ECM receives one voltage pulse per ring gear tooth. The voltage signal is used by ECM to determine engine speed, and to calculate ignition and injection firing points. ECM will not allow engine to start if RPM sensor signal is not received within 5 seconds. If RPM sensor fails while engine is running, engine will stop running immediately. RPM sensor is adjusted at factory. If sensor bracket is removed, mark position of bracket on cylinder block for reassembly reference.