Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31
• ◆ VAS 5051 with VAS 5051/1

• or

• ◆ V.A.G 1551 with V.A.G 1551/3 A

Test requirements:

• ● Coolant temperature at least 80 °C.
• ● Electrical consumers switched off (radiator fan must not run during the test).
• ● Air conditioning switched off.
• ● Fuse for air mass meter OK.

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

checking function

• ‒ Connect 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

• ‒ Enter "04" to select "Start basic setting" and confirm 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.

• ‒ Enter "002" for "display group number 002" and confirm entry with Q key.

• ‒ Check specified values for load recognition in display zones 3 and 4.

1)    2.4 litre front and four-wheel drive 2) 2.8 litre front wheel drive 3) 2.8 litre four-wheel drive

If specified values are attained:

• ‒ Press the ⇒key.

Interpreting display group 002

Interpreting display group 002

Testing voltage supply to air mass meter

• ‒ Disconnect connector from intake air temperature sensor.

• ‒ → Connect multimeter as follows to measure voltage.

• ‒ Operate starter briefly.
• ‒ Specified value: approx. battery voltage

Note:

Voltage supply to airflow meter is from fuel pump relay.

If specified value is not attained:

• ‒ Check the wiring from contact 3 on the connector via the fuse to the fuel pump relay for open circuit or short to earth:

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

• ‒ Rectify any open/short circuit as necessary.

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

Note:

Engine control unit earth is present at contact 2 of the connector.

If specified value is not attained:

• ‒ Check the wiring connections
  .

• ‒ → Connect hand-held multimeter to contact 1 and contact 2 of the connector to measure voltage.
• ‒ Switch the ignition on.
• ‒ Specified value: approx. 5 V

If specified value is not attained:

• ‒ Check the wiring connections
  .

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 24-17.

• ‒ → Check for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify any open/short circuit as necessary.
• ‒ Additionally check all wires for short to one another.

If the wiring is OK:

• ‒ Renew air mass meter -G70.