Audi Workshop Service and Repair Manuals

If performance faults occur after a cold start, check whether the problem arises before or after the lambda control cuts in.

Test conditions

• ● No fault stored in fault memory
  , Interrogate fault memory.

• ‒ Read measured value block, Display Group 21, engine at idling speed => Page 01-49.

• ‒ Take the vehicle for a test drive.

• ‒ Check display in display zone 4.

• Specified result: λ-l-Control OFF (lambda control not active)

If the engine running problems occur before the lambda control cuts in, the following faults are possible:

• ◆ Carbon deposits on the inlet valves.
• ◆ Unmetered air in intake system.
• ◆ Fuel supply system defective.

The lambda control cuts in at a probe temperature of approx.
300°C. The time it takes for this temperature to be reached is influenced by the following factors:

• ◆ Ambient temperature (summer or winter).
• ◆ Operating conditions after starting.
• ◆ Operation of lambda probe heating.

• ‒ Check display in display zone 4.

• Specified result: λ-Control ON (lambda control active)

If the engine running problems only occur after the lambda control sets in:

• ‒ Check function => Page 24-43