Fuel Temperature Sensor, Checking
Fuel Temperature Sensor, Checking
NOTE: Use only gold-plated terminals when servicing terminals in harness connector to injection pump quantity adjuster.
Recommended special tools and equipment
- V.A.G1526 multimeter or V.A.G1715 multimeter
- V.A.G1594 connector test kit
- Wiring diagram
Test requirement
- The respective fuses of Diesel-Direct fuel injection system must be OK:
- Battery voltage must be at least 11.5 volts.
Test sequence
Vehicles with engine code ALH
- Disconnect 10-pin harness connector (arrow) for fuel temperature sensor (harness connector to injection pump quantity adjuster).
- Measure resistance of sensor at connector terminals 4 + 7.
See diagram for specified value
Range A displays resistance values for the temperature range of 0 to 50 degrees C, range B displays resistance values for the temperature range of 50 to 100 degrees C.
Read-out examples:
- 30 degrees C corresponds to a resistance of 1500 to 2000 Ohms
- 80 degrees C corresponds to a resistance of 275 to 375 Ohms
If specified value is not obtained:
- Replace injection pump.
- Erase DTC memory of control module for Diesel-Direct fuel injection system, Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If specified value is obtained:
- Check wires to control module according to wiring diagram.
Vehicles with engine code BEW
- Disconnect 2-pin harness connector (arrow) for fuel temperature sensor.
- Measure resistance between terminals 1 + 2 on sensor.
See diagram for specified value
Range A displays resistance values for the temperature range of 0 to 65 degrees C, range B displays resistance values for the temperature range of 65 to 100 degrees C.
Read-out examples:
- 30 degrees C corresponds to a resistance of 3790 to 4270 Ohms
- 80 degrees C corresponds to a resistance of 600 to 660 Ohms
If specified value is not obtained:
- Replace Fuel Temperature Sensor -G81-.
- Erase DTC memory of control module for Diesel-Direct fuel injection system, Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If specified value is obtained:
- Check wires to control module according to wiring diagram.
Check wires to control module
- Connect test box to control module wiring harness, connect test box for wiring test. Test Box, Connecting For Wiring Test
Vehicles with 80-pin control module
- Check for open circuits in wires between test box and connector according to wiring diagram.
Terminal 4 + socket 76
Terminal 7 + socket 53
Wire resistance: max. 1.5 Ohms
Vehicles with 121-pin control module
- Check for open circuits in wires between test box and connector according to wiring diagram.
Terminal 7 + socket 111
Terminal 4 + socket 103
Wire resistance: max. 1.5 Ohms
Vehicles with 154-pin control module
- Connect adapter cable (V.A.G 1598/39-1) to test box (V.A.G 1598/42).
- Check for open circuits in wires between test box and connector according to wiring diagram.
Terminal 1 + socket 40
Terminal 2 + socket 39
Wire resistance: max. 1.5 Ohms
Continue for all vehicles
- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
Specified value: Infinite Ohms
If no malfunctions are found in wires:
- Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248-.
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes