Impreza F4-2.5L SOHC (2003)
Fuel Gauge: Description and Operation
FUEL GAUGE
GENERAL
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The fuel gauge unit consists of a float and a potentiometer whose resistance varies depending on movement of the float. It is located inside the fuel
tank and forms an integral part of the fuel pump. The fuel gauge indicates the fuel level in the tank even when the ignition switch is in the LOCK
position.
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All models are equipped with two fuel level sensors. These sensors are installed in the fuel tank, one on the right side and the other on the left side.
Two sensors are necessary because the fuel tank is divided into main and sub tank compartments
OPERATION
The low fuel warning light operates as follows:
The combination meter CPU continually monitors the resistance signal from the fuel level sensor. It turns on the low fuel warning light if a resistance
value corresponding to the critical fuel level (approx. 78 Ohms) is detected successively for about 10 minutes or the period spent for driving a distance
of 10 km.
This monitoring time has been decided to avoid false operation of the warning light which may happen when a large part of remaining fuel is collected
temporarily in the sub tank compartment.