Audi Workshop Service and Repair Manuals

The air mass meter signal is used by the control unit to calculate the quantity injected and to control the required exhaust gas recirculation. The smaller the signal from air mass meter the smaller the quantity of fuel injected.

Test sequence

• ‒ Read data block, Display group 010, engine idling=>Page01-127.

→ Display on VAS 5051:

• ‒ Check display in display zone -1-.
• ‒ Specification for 74 kW engine: 200 ... 370 mg/stroke
• ‒ Specification for 96 kW engine: 210 ... 350 mg/stroke

If the specification is not obtained:

• ‒ Check exhaust gas recirculation:

=> 4-Cyl. TDI engine, Mechanics; Repair group 26; Exhaust gas recirculation system

If the specification is obtained:

• ‒ Accelerate from 2000 rpm at full throttle (without kick-down) in third gear (or with selector lever at position 2), and watch rev counter.
• ‒ Press PRINT key on V.A.G 1551 at approx. 3000 rpm. The accelerator pedal must be fully depressed at this moment in time.

→ Display on VAS 5051:

• ‒ Check readout in display zone -4-.
• ‒ Specification: 100 % (accelerator position)
• ‒ Repeat test and accelerate vehicle at full throttle.
• ‒ Check display in display zone -1-.
• ‒ Specification for 74 kW engine: > 800 mg/stoke (intake air mass)
• ‒ Specification for 96 kW engine: > 900 mg/stoke (intake air mass)
• ‒ Press the ◂ button to exit from the function "08 - Read data block".
• ‒ Select diagnosis function "06 - End output".
• ‒ Switch off ignition.

If the specification is not obtained:

• ‒ Fit a new air mass meter -G70.

If a constant 539 mg/H (predetermined substitute value) is displayed in display zone 1.

• ‒ Check voltage supply.

Checking voltage supply

• ‒ Unplug connector for air mass meter -G70
  =>Fitting locations overview, Page23-7, Item 14.
• ‒ → Connect multimeter (voltage measurement range) as follows:
• ‒ Switch on ignition.

If the specifications are not obtained:

Checking wiring connections

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit.Do notconnect to the engine control unit itself:
• ‒ Connecting test box to engine control unit without protective housing=>Page 23-49.
• ‒ Connecting test box to engine control unit with protective housing=>Page 23-51.

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

• ‒ Rectify any open/short circuit as necessary.

If no fault is found:

• ‒ Replace engine control unit
• ‒ Removing and installing engine control unit without protective housing=>Page 23-57.
• ‒ Removing and installing engine control unit with protective housing=>Page 23-60.