Audi Workshop Service and Repair Manuals

Test conditions

• ● Coolant temperature at least 80 oC (display group 4, display zone 3).
• ● Electrical consumers switched off (radiator fan must not run during the check)
• ● Air conditioner switched off
• ● Fuse for airflow meter OK.

=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations

checking function

• ‒ Connect up vehicle diagnostic, testing and information system VAS 5051 or fault reader V.A.G 1551 and select engine electronics control unit with "Address word" 01 .
  For this purpose, the engine must be running at idle speed

• ‒ Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with Q key.

Note:

During basic setting, the solenoid valve for the active carbon canister (valve N80) is closed and the air conditioner compressor is switched off by the engine control unit.

• ‒ Press keys 0, 0 and 2 for "display group 2" and confirm entry with Q key.

• ‒ Check specified results for recorded load.

If specified value is attained:

• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and press the Q key to confirm entry.
• ‒ Switch ignition off.

Interpreting display group 2

Interpreting display group 2

Testing voltage supply to air mass meter

• ‒ → Disconnect connector from air mass meter.
• ‒ Connect hand-held multimeter (voltage test range) between engine earth and contact 2 on the connector.
• ‒ Operate the starter briefly.

• Specified value: approx. battery voltage

Note:

Voltage supply to airflow meter is from fuel pump relay.

If battery voltage is not present:

• ‒ Test wiring from contact 2 on connector via fuse to fuel pump relay for open circuit or short to earth. Rectify if necessary.

=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations

• ‒ → Connect hand-held multimeter to contact 2 and contact 3 of the connector to measure voltage.
• ‒ Operate the starter briefly.

• Specified value: approx. battery voltage

Note:

Engine control unit earth is present at contact 3 of the connector.

If specified value is not attained, check wiring => Page 24-69.

• ‒ → Connect hand-held multimeter to contact 3 and contact 4 of the connector to measure voltage.
• ‒ Switch the ignition on.

• Specified value: approx. 5 V.

If specified value is not attained, check wiring => Page 24-69.

Check wiring to airflow meter.

Note:

The signal wire is also checked during the wiring check.

• ‒ Connect the V.A.G 1598/31 test box to wiring harness leading to engine control unit; the engine control unit should not be connected => Page 24-22.

The following wiring connections are to be checked for open circuits and/or short to positive or negative.

• Wire resistance: max. 1.5 Ohm

• ‒ Additionally check all wires for short to one another.

• Specified value: infinite resistance (open circuit)

• ‒ If the voltage supply and the wiring are OK, renew the airflow meter (G70).