Bosch Motronic - Component Datasheet
Engine Speed Sensor (G28)
The Engine Speed Sensor (ESS), referred to as G28 on the schematic, is used by the ECU to determine the engine speed. It does this by generating a saw-tooth waveform as teeth on the flywheel induce a voltage across the tip of the sensor. The ECU counts the number of these pulses over time and calculates the instantaneous engine speed.
is located on the left side of the engine near the flywheel. It is mounted
alongside the crankshaft reference sensor (G4) and care must be taken not to
confuse the wiring of these two sensors as they are identical in design.
G28 fails, the engine cannot be restarted.
Last Updated 9th November 2007