Audi Workshop Service and Repair Manuals

Test requirements:

• ● Vehicle diagnostic, testing and information system VAS 5051 connected, vehicle self-diagnosis and vehicle system "01 - Engine electronics" selected.

• ◆ To localise faults, the turbocharger (without boost pressure control) must be checked first, followed by the boost pressure with boost pressure control.

Checking without boost pressure control:

• ‒ → Disconnect electrical connector at boost pressure limitation solenoid valve -N75 -Item 2-.

→ Display on VAS 5051:

• ‒ Under -1- select the diagnostic function "08 - Read measured value block".

→ Display on VAS 5051:

•     1 -    Enter display group
  max. input value = 255

• ‒ Enter "011" for "display group number 011" in zone -2- and confirm the entry by pressing the Q button.
• ‒ Fully accelerate the vehicle from 2000 rpm in third gear or with selector lever at position 2 (without kickdown) and observe rev counter.
• ‒ At approx. 3000 rpm press the key "Print - Save result" on the VAS 5051.

• ‒ Exit the function "08 - Read measured value block" by pressing the ◂key.
• ‒ If measured boost pressure is OK, repeat boost pressure measurement with boost pressure control=> Page 21-9.

If boost pressure is not obtained:

• ◆ Leak between turbocharger and intake manifold
• ◆ Fault is in boost pressure control linkage or vacuum unit. Checking => Page 21-15
• ◆ Turbocharger defective (turbine blocked due to foreign body)

If boost pressure is exceeded:

• ◆ Boost pressure control hoses fallen off, leaking or blocket.
• ◆ Boost pressure limitation solenoid valve restricted
• ◆ Bypass valve actuator (linkage, shaft) binding or stuck (bypass valve always closed)

Checking with boost pressure control:

• ‒ → Attach electrical connection to boost pressure limitation solenoid valve -N75 -Item 2-.
• ‒ Erase fault memory.

=> Diesel Direct Injection and Glow Plug System (4-cyl TDI) > 07.99; Repair group 01; Self-diagnosis; Interrogating fault memory

=> TDI Injection and Glow Plug System (4-cyl.) 08.99 >; Repair group 01; Self-diagnosis; Interrogating fault memory

Note:

Disconnecting boost pressure limitation solenoid valve electrical connection -N75 caused a fault code to be set in the fault memory during the previous testing procedure.

→ Display on VAS 5051:

• ‒ Under -1- select the diagnostic function "08 - Read measured value block".

→ Display on VAS 5051:

•     1 -    Enter display group
  max. input value = 255

• ‒ Enter "011" for "display group number 011" in zone -2- and confirm the entry by pressing the Q button.
• ‒ Fully accelerate the vehicle from 2000 rpm in third gear or with selector lever at position 2 (without kickdown) and observe rev counter.
• ‒ At approx. 3000 rpm press the key "Print - Save result" on the VAS 5051.

• ‒ Exit the function "08 - Read measured value block" by pressing the ◂key.
• ‒ Press "06 - Exit output".

If boost pressure is not obtained:

• ◆ No electrical function of boost pressure limitation solenoid valve.
• ◆ Boost pressure limitation solenoid valve -N75 is stuck in the open position

If boost pressure is exceeded:

• ◆ Solenoid valve for boost pressure limitation -N75 intermittently stuck closed.
• ◆ Boost pressure increased as a result of tuning