Audi Workshop Service and Repair Manuals

The operation of the exhaust gas recirculation system is tested by measuring the intake air mass. If exhaust gas is being recirculated the proportion of fresh air detected by air mass meter will be smaller. The larger the quantity of recirculated exhaust gas, the weaker the signal from the air mass meter.

Special tools, testers and auxiliary equipment required

• ◆ VAS 5051

or

• ◆ V.A.G 1551 with V.A.G 1551/3 A

Test requirements:

• ● Coolant temperature at least 80 °C.

Test sequence

• ‒ Read measured value block, display group 001:

=> Diesel direct-injection and glow lamp system (4-cyl.) ä 06.97; Repair group 01; Self diagnosis of diesel direct-injection system; Reading measured value block

• ‒ Check display in display zone 4 (coolant temperature).
• ‒ Specified value: at least 80 °C
• ‒ Do not continue with the test until the coolant has reached the specified temperature.
• ‒ Read measured value block, display group 003.

• ‒ Briefly depress the accelerator pedal, then allow the engine to continue running at idling speed.

• ‒ Observe displays in display zones 2 and 3

Note:

If display zone 3 shows a constant reading of 425 mg/stroke, test air mass meter:

=> Diesel direct injection and glow plug system (4 cyl.) ä 06.97; Repair group 23; Servicing diesel direct-injection system; Testing air mass meter

If the specified values are not obtained:

• ‒ Start final control diagnosis and actuate EGR valve -N18:

=> Diesel direct-injection and glow lamp system (4-cyl.) ä 06.97; Repair group 01; Self diagnosis of diesel direct-injection system; Final control diagnosis

• The injector valve should click.

If the injector does not click:

• ‒ Check EGR valve -N18

If the injector clicks:

• ‒ Check vacuum hoses => Page 26-32.

If vacuum hoses are OK:

• ‒ Test mechanical exhaust gas recirculation valve => Page 26-34.