1. Connect tester VAG 1551 and dial «01» to select a function «Address word» engine control unit. The engine must be running at idle. The display should show the following information:
2. Click «08» to select a function «Reading a block of measured values» and confirm by pressing the button «Q». The display should show the following information:
3. Click «002» to select a function «Group 2 display» and press «Q». The display should show the following information:
4. Read the temperature of the incoming air in field 4 of the display.
Continue testing at -33°C
5. Disconnect harness connector 1 from sensor 2 (pic. 3.37).
6. Shunt pins 1 and 2 of the wiring connector using auxiliary wires from the VAG 1594 tester and observe the readings on the display.
Approximately 118°C on the display:
- click «→»;
- click «06» to select a function «Output Completion» and confirm by pressing the button «Q»;
- turn off the ignition;
- replace the intake air temperature sensor 2.
Approximately -33°С on the display:
- click «→»;
- click «06» to select a function «Output Completion» and confirm by pressing the button «Q»:
- turn off the ignition;
- connect the tester VAG 1598/18 to the wiring harness of the engine control unit;
- check the wire between the tester and the connector for an open circuit: socket 43 of the tester and pin 2 of the four-pin wiring connector (rice. 3.34). Set value: max. 1.5 ohm.
- check the wires for a short to positive. Set value: ∞ Ohm.
- check the wire between the tester and the connector for an open circuit: socket 17 of the tester and pin 1 of the four-pin wiring connector. Set value: max. 1.5 ohm.
7. If no fault is found in the wires, then replace the engine control unit.
Continue testing at 118°C
8. Disconnect harness connector 1 from sensor 2 (pic. 3.37).
9. Shunt pins 1 and 2 of the wiring connector using auxiliary wires from the VAG 1594 tester and observe the readings on the display.
Approximately -33°С on the display:
- click «→»;
- click «06» to select a function «Output Completion» and confirm by pressing the button «Q»;
- turn off the ignition;
- replace the intake air temperature sensor 2.
Approximately 118°C on the display:
- click «→»;
- click «06» to select a function «Output Completion» and confirm by pressing the button «Q»;
- turn off the ignition;
- disconnect the wiring connector of the engine control unit;
- check the wire to pin 2 of the four-pin engine control unit wiring connector for a short to pin 1 of the wire and to «mass». Set value: ∞ Ohm.
10. If no fault is found in the wires, then replace the engine control unit.
Continued test at ambient temperature
11. Remove the intake air temperature sensor (wiring connector remains connected) (pic. 3.38).
12. Take note of the temperature value in field 4 of the display.
13. Spray the sensor with coolant while observing the temperature reading. She share to go down.
14 Press «→».
15. Click «06» to select a function «Output Completion» and confirm by pressing the button «Q».
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