Fuel Temperature Sensor: Testing and Inspection

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Special tools, workshop equipment, testers, measuring instruments and auxiliary items required
- VAG 1551/1552 Scan Tool using VAG 1551/3 adaptor cable
- VAG 1598/22 Test Box
- Fluke 83 multimeter
- VW 1594 Adaptor kit
- Wiring diagram

Test sequence

- Connect VAG 1551/1552 Scan Tool. Testing and Inspection
- Start engine and let idle
- Press 0 and 1 buttons to select Address word 01: "Engine electronics"

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 measunng value block HELP
Input display group number XXX


- Press 0, 0 and 7 buttons to select "Display group 7"
- Press 0 button to enter input

Display will appear as shown


Read measuring value block 7 ->
15.4 °C 15.9 °C 16.7 °C


- If an un-realistic value appears in display zone 1, or a substitute temperature of -5.4 °C is displayed, check the Fuel temperature sensor and wiring to sensor as follows:
- Press -> button.
- Press 0 and 6 buttons to select Function 06: "End transfer"
- Press Q button to enter input
- Switch OFF ignition.
- Disconnect 10-pin Fuel temperature sensor harness connector







- connection to injection pump metering control
- Measure sensor resistance at terminals 4 + 7
- Specification: correlate resistance measurement with chart







NOTE: Scale A shows resistance values for range 0 to 50 °C and scale B shows the values for range 50 to 100 °C.


Examples:
- 30 °C corresponds to a resistance from 1500 to 2000 Ohms
- 80 °C corresponds to a resistance from 275 to 375 Ohms

If specification not obtained
- Replace injection pump. Service and Repair

If DTC memory has been erased
- Create Readiness code. Testing and Inspection

If specification obtained
- Connect VAG 1598/22 Test Box to ECM wiring harness.







- Check wiring for open circuit between Test Box and harness connector using Wiring diagram.
- Terminal 7 + socket 53
- Terminal 4 + socket 76
- Wire resistance: max. 1.5 Ohms







- Check wires for short to one another, to vehicle Ground and to battery Plus.
- Specification: Infinity Ohms

If wiring OK
- Replace Diesel direct injection system ECM J248.
- Display Readiness code. Testing and Inspection

If DTC memory has been erased
- Create Readiness code. Testing and Inspection