Note: Idle speed and CO content must be checked together. They cannot be adjusted.
Warm up the engine, oil temperature 80°C.
Turn off all electrical consumers.
Check the exhaust system for leaks.
Check the lambda adjustment, for which read the contents of the fault memory.
Check the ignition timing.
Caution: Connect test devices only when the ignition is off.
Connect the tachometer according to the instructions.
Connect the CO content measuring device to the measuring pipe. The measuring pipe is welded to the exhaust pipe and is usually plugged with a blue plug.
Caution: Push the measuring instrument hose firmly onto the connection piece.
Make sure there are no leaks.
Start the engine and let it idle.
Note: The radiator fan must not operate during the test.
Check the idle speed, it should be: 750-950 rpm.
Check the CO content, it should be 0.2-1.2%.
The CO content and idle speed are not adjustable. If they deviate from the required value, check all low-pressure hoses for porosity and fastening strength.
Check the fastening of the injection unit and the tightness of the flange.
Have the magnetic valve I (gray) of the activated carbon filter box checked.
Read information from error memory.
Turn off the test devices when the ignition is off.
(The original article is posted on the resource: AudiManual.ru)