Reducing Agent, Automatic Recirculation

WARNING: This page is about a different car, the 2021 Audi S4 and 2021 Audi A4 Quattro. However, it is still accessible from the selected car via links, so may be relevant.

After switching off the ignition, the reducing agent flows back into the reducing agent tank via the metering line to the Reducing Agent Injector -N474-.
Before working in this area, wait at least 10 minutes after switching off the ignition so that the recirculation process can be completed.
Also wait 10 minutes after switching off the ignition before disconnecting the battery so that the recirculation process can complete. Refer to BATTERY, DISCONNECTING AND CONNECTING .

CAUTION:

The Reducing Agent Increase the Risk of Damage

If any reducing agent contacts the trim or body components, the reducing agent can crystallize after a period of time and damage the surface.

-- Make sure the reducing agent does not contact any trim or vehicle body components.

-- If any contact occurs on surfaces, remove the reducing agent immediately using water and a towel.