With Manufacturer's Scan Tool

Fuel Temperature Sensor -G81-, Checking

NOTE: Only gold-plated contacts must be used when repairing terminals in the connector to the injection pump metering unit.

Special tools and equipment
- Scan Tool VAG 1551 or vehicle system tester
- VAG 1552 with cable VAG 1551/3
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Test sequence
- Connect VAG 1551/1552 (Connecting scan tool and selecting engine electronics control module.) Run engine at idle speed and press buttons -0- and -1- to select "Engine electronics" address word 01. [1][2][3]Connecting VAG 1551 Scan Tool

Indicated on display:

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- for the function "Read measured value block" and confirm entry with - Q- button.

Indicated on display:

Read measured value block
Enter display group number XXX

- Press buttons -0-, -0- and -7- for "Display group number 7" and confirm entry with -Q- button.

Indicated on display:

Read measured value block 7
15.4 degree C 15.9 degree C 16.7 degree C

- If no realistic display appears in display field 1 or a substitute temperature of -5.4 degree C is displayed, check fuel temperature sensor and wiring to the sensor as follows:
- Press the -> button.
- Press buttons -0- and -6- for the function "End output" and confirm entry with the -Q- button.

- Switch off ignition.






- Disconnect 10-pin connector for fuel temperature sensor -G81- (connection to injection pump metering unit) -arrow-.






- Measure sensor resistance at connector terminal 4+7.






Specification see diagram
Scale A shows resistance values for temperature range 0 to 50 degree C and scale B the values for temperature range 50 to 100 degree C.

Examples:
- 30 degree C corresponds to a resistance from 1500 to 2000 Ohm
- 80 degree C corresponds to a resistance from 275 to 375 Ohm

If the specification is not obtained:
- Replace injection pump.
- Check DTC memory and, if necessary, repair any malfunctions and then erase. [1][2]Reading Diagnostic Trouble Codes
- Read readiness code. If the DTC memory has been erased or the Diesel Direct Fuel Injection Engine Control Module - J248- was disconnected from permanent battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes

If the specification is obtained:
- Remove wiper arms and plenum cover.






- Connect test box VAG 1598/31 to control module wiring harness.






- Check wiring between test box and connector for open circuit according to wiring diagram.
Terminal 7 + socket 111
Terminal 4 + socket 103
Wire resistance: max. 1.5 Ohm
- Check wires for short to one another, to vehicle Ground and to battery positive (B+).
Specification: Infinite Ohm

If no fault is detected in the wiring:
- Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248-.