DTC 00539

DTC Code 00539, Fuel Temperature Sensor (G81):
Short To Ground
or
Open Circuit, Short To Positive

Special Tools, Testers And Auxiliary Items
- VAG 1598/18 Test Box adaptor
- Fluke 83 Multimeter or equivalent
- VW 1594 Adaptor kit
- Wiring diagram

Work Sequence:
Display will appear as shown:

Rapid data transfer HELP
Select function XX

- Press 0 and 8 buttons to select Function 08 "Read measuring value block"
- Press Q button to enter input
Display will appear as shown:

Read measuring value block HELP
Input display group number XX

- Press 0 and 7 buttons for "display number 07"
- Press Q button to enter input
Display will appear as shown:

Read measuring value block 7 "
15.45C 15.95C 16.75C

If an un-realistic display appears in channel 1 or a substitute temperature of -5.6°C (21.92°F) is displayed, check Fuel Temperature sensor G81 and wiring connections to sensor as follows:
- Press -> button
- Press 0 and 6 buttons to select Function 06 "End data transfer"
- Press Q button to enter input
- Turn OFF ignition





- Disconnect Fuel Temperature sensor G81 harness connector connection to injection pump metering control
- Measure sensor resistance at terminals 4 + 7





Resistance graph for Fuel Temperature sensor G81
Scale A shows resistance values for temperature range 0 to 50°C
Scale B shows the values for temperature range 50 to 100°C

Examples:
- 30°C (86°F) corresponds to a resistance from 1500 to 2000 ohm
- 80°C (176°F) corresponds to a resistance from 275 to 375 ohm

If specified resistance not obtained:
- Replace Fuel Temperature sensor G81

If specified resistance is obtained
- Connect VAG 1598/18 Test Box adaptor to ECM wiring harness
- Check wiring for open circuit between VAG 1598/18 Test Box adaptor and harness connector using wiring diagram:
Terminal 7 + socket 63
Terminal 4 + socket 33
Wire resistance: 1.5 ohm maximum

- Check for shorting between wires
Specification: infinite ohm

If no malfunction found:
- Replace ECM J248