Audi Workshop Service and Repair Manuals

• ‒ Select "Read measured value block" (function 08) and Display Group 01
  .

Do not proceed with the test until the coolant temperature shown in display zone 2 has reached at least 80 °C.

Display zone 3 will show the voltage of the lambda probe signal.

• ‒ If the lambda probe voltage reading fluctuates very slowly, test the lambda probe heating => Page 24-62.
• ‒ Press ⇒key.
• ‒ Select "Read measured value block" (function 08) and Display Group 99
  => Page 01-107.

Display zone 4 will show the status of the Lambda control.

Relevance of figures in 8-digit number block in display zone 4 (see also Page 01-107):

If the lambda control has reached one of its stop limits (i.e. if the "Lambda control at stop limit" space contains a "1"), the "Mixture status" space will indicate which of the stops the lambda control is at.

If the Lambda control has reached a stop limit and the "Mixture status" space is showing a "1" continuously, this means that the Lambda control is at the maximum leaning-down limit but the Lambda probe is still registering "Mixture too rich".

If the Lambda control has reached a stop limit and the "Mixture status" space is showing a "0" continuously, this means that the Lambda control is at the maximum enrichment limit but the Lambda probe is still registering "Mixture too lean".

Note:

If the Lambda control remains at either of the stop limits ("too rich" or "too lean") for a certain period of time a fault will be recorded in the fault memory.

• ‒ If the Lambda control is functioning properly, check the Lambda learned values.
• ‒ Press C key.
• ‒ Press keys 0, 1 and 1 for display group 11 and confirm entry by pressing Q.

Note:

The mixture adaption system has learning ability, i.e. the Lambda control can recognise differences between various engines (injector nozzle delivery, compression, fuel pressure etc.) and compensates by adjusting the pre-programmed basic injection periods in the map in the control unit. The injection periods are extended or reduced until a mixture composition of "λ = 1" is achieved.

Display zone 2 shows the Lambda learned value for idling.

• ◆ Positive learned value (+...ms): Pre-programmed basic injection period is too short, actual injection period ...ms longer in order to achieve a "λ = 1" mixture composition.
• ◆ Negative learned value (-...ms): Pre-programmed basic injection period is too long, actual injection period ...ms shorter in order to achieve a "λ = 1" mixture composition.

Display zone 3 shows the Lambda learned value for part throttle.

• ◆ Values greater than 1: Pre-programmed basic injection period is too short, actual injection period longer in order to achieve a "λ = 1" mixture composition.
• ◆ Values less than 1: Pre-programmed basic injection period is too long, actual injection period shorter in order to achieve a "λ = 1" mixture composition.

Specifications: => Page 01-94.