Fuel Temperature Sensor G81 - Volkswagen 1.9-Liter TDI Owner's Manual

Fuel Temperature Sensor G81

The Fuel Temperature Sensor G81 is
located in the fuel return line between the
fuel pump and the fuel cooler. It determines
the current temperature of the fuel at
that point.
The Fuel Temperature Sensor G81 has a
negative temperature coefficient. The
sensor resistance decreases with
increasing fuel temperature.
Signal application
The signal generated by the Fuel
Temperature Sensor G81 is used by
the Diesel Direct Fuel Injection Engine
Control Module J248 to determine
the fuel temperature.
This signal is needed to calculate the
start of injection point and the injection
quantity so that allowance can be made
for the density of the fuel at different
temperatures.
This signal is also used to determine
the timing for switching on the fuel
cooling pump.
Effects of signal failure
In the event of Fuel Temperature Sensor
G81 signal failure, the Diesel Direct Fuel
Injection Engine Control Module J248
calculates a substitute value from the signal
generated by Engine Coolant Temperature
Sensor G62.
Electrical circuit
G81 Fuel Temperature Sensor
J248 Diesel Direct Fuel Injection Engine
Control Module
Engine Management
SSP209/043
J248
G81
SSP209/058
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