Audi Workshop Service and Repair Manuals

• ‒ Check the CO2 (carbon dioxide) content in the additional heater exhaust gas

Note:

For the adjusting of the CO2-content in the exhaust gas:

• ‒ the additional heater must operate under full load.
• ‒ is the vehicle diagnostic, testing and information system VAS 5051 connected and the additional heater self-diagnosis initiated.
• ‒ if the CO2-measuring unit is ready for operation and the exhaust measuring probe is attached to the exhaust pipe of the additional heater in such a way that the exhaust outlet is not obstructed.

→ Display on VAS 5051:

• ◆ The following display appears in area -2-:
• ‒ Basic setting
• ‒ Additional heating
• ‒ Heating

Notes:

• ◆ If another or an additional display appears in the area -2- then eliminate the cause of the fault => Page 01-49
• ◆ Following entry of the "display group 022" in the basic setting function approx. 8 min. remain in order to perform adjustment of the CO2-content. If the time is not sufficient the process can be repeated.

• ‒ Press the ← key

→ Display on VAS 5051:

• ‒ Select function "10 - Adaption".

→ Display on VAS 5051:

• ◆ The prompt to enter a channel number is given in display zone -1-.
• ◆ An input keyboard is displayed in display zone -2-.

• ‒ Enter "02" for "Channel 2" using the input keyboard in display zone -2- and confirm entry with "Q key".

→ Display on VAS 5051:

• ◆ The message "Read and test channel 2" appears in display zone -1-.
• ◆ "CO2-setting" appears in area -2-.
• ◆ A scroll bar appears in area -3- with the encoded value of the currently valid "CO2-setting" (e.g. "126" as adjusted at the factory).

Notes:

• ◆ After pressing key -4- the desired adjustment value may also be entered directly via the keyboard => Page 82-41

• ◆ → If the message "Function unknown or cannot be executed at present" appears in display zone -1- this may have the following cause:

• ‒ The additional heater was switched on and is currently in "run-on" operating status (Interrogate current operating status => Reading measured value block Page 01-67)
• ‒ A fault is stored in the auxiliary heater which does not permit switching on.

• ◆ → If "Wait" appears in area -2-, the additional heater is in an operating status where the adjustment of CO2-content is not possible, e.g. during starting sequence.
• ‒ Wait until the display switches to "CO2-setting".
• ‒ If the display "Wait" is displayed longer than 5 minutes then interrogate the fault memory, a fault has occurred.

• ‒ Using the scroll bar -3- the CO2-content in the additional heater exhaust gas can be altered within the specified limits (e.g. from "105" and "136", the actual limits of the adjustment are dependent on the basic setting for this unit by the additional heater manufacturer).
• ‒ By sliding the scrollbar to the left (in direction of "0") the combustion air blower speed is reduced and the CO2-content increases.
• ‒ By sliding the scrollbar to the right (in direction of "262") the combustion air blower speed is increases and the CO2-content decreases.
• ‒ The CO2-content changes by approx. 0.08 % by volume per scroll bar unit.

• ‒ Read measured value for the CO2 (carbon dioxide) content from CO2-measuring unit.
• ‒ → Slide the scroll bar -3- in the desired direction (e.g. by 5 units to the left if the CO2-content in the exhaust gas is to be increased by 0.4%).

Setting:

• ◆ Diesel engine
  9 to 12 % CO2 by volume.

Notes:

• ◆ The scroll bar -3- can be moved between "0" and "262". However, an adjustment within a range of only "105" and "136" is provided in the additional heater control unit to set the CO2-content.
• ◆ If the scroll bar -3- jumps back into the initial position after releasing, the specified adjustment range was exceeded.

Following adjustment of the scroll bar -3- the key -5- appears on the display.

• ‒ Save the altered value by pressing key -5-.

→ Display on VAS 5051:

• ◆ The message "Save channel 2" appears in display zone -1-.
• ◆ In area -3- the original and the new value for the "CO2-adjustment" appear encoded.

• ‒ Accept and save your entry by pressing the key -4-.

• ◆ The message "Save channel 2, value 1 saved" appears in display zone -1-.

• ‒ Wait approx. 1 minute (until the altered CO2-content is properly indicated on the measuring unit.
• ‒ Read measured value for the CO2 (carbon dioxide) content from CO2-measuring unit.

Setting:

• ◆ Diesel engine
  9 to 12 % CO2 by volume.

Notes:

• ◆ By pressing the ←key you will return to the selection program.

• ◆ If the additional heater is switched off during the CO2-adjustment or leaves the full load operation the value stored before adjustment remains valid. In this case, repeat the procedure again.
• ◆ The CO2-content can only be altered within certain limits (from approx. "00105" to "00136"). If the CO2-content cannot be adjusted as required please check the combustion air blower with air intake area, the fuel delivery rate of the metering pump and the exhaust system of the additional heater.

• ‒ Switch off the additional heater via the function "Basic setting, display group 33" => Page 01-49

Altering CO2-content in the exhaust gas with keyboard entry

→ Display on VAS 5051:

• ‒ Press the -4- key.

→ Display on VAS 5051:

• ◆ The message "Enter adaption value" appears in display zone -1-. 0...XXXXX".
• ◆ An input keyboard is displayed in display zone -2-.

• ‒ Enter the desired value for the CO2-content in display zone -2- using the input and confirm entry by typing the "Q key".
• ‒ Then proceed as for adjustment using the scroll bar.