Genuine BMW 64115A35099 xAUC Automatic Air Recirculation Control Sensor

The Genuine BMW xAUC Sensor (Part #64-11-5-A35-099) is an OEM replacement automatic air recirculation control (AUC) sensor for BMW F-chassis 5 Series, 6 Series, 7 Series, X3, and X4 models. This is a Genuine BMW factory part manufactured to original equipment specifications.

The AUC (Automatic Air recirculation Control) sensor continuously monitors outside air quality by detecting harmful combustion gases including carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NOx). When pollutant levels exceed safe thresholds, the sensor automatically signals the HVAC system to switch to recirculated cabin air, protecting occupants from exhaust fumes and other airborne contaminants. When outside air quality improves, the system automatically returns to fresh-air mode.

Key Features:

• Genuine BMW OEM part — manufactured to factory specifications
• Detects CO, HC, NOx, and other combustion-related pollutants in real time
• Automatically triggers HVAC recirculation mode when air quality drops
• Located in the engine bay near the radiator or microfilter/Bowden cable area
• Direct plug-and-play replacement — no modifications required
• Latest design revision, superseding multiple earlier part numbers

Supersedes the following BMW part numbers: 64-11-6-826-346, 64-11-6-822-554, 64-11-6-818-831, 64-11-9-350-423, 64-11-9-305-877, 64-11-9-123-861

A failed AUC sensor can cause erratic HVAC behavior such as the blower speed or temperature controls not responding as expected, the system cycling on and off unpredictably, or diagnostic fault codes being stored in the HVAC control module. Replacing with a Genuine BMW sensor restores proper automatic air recirculation function and cabin air quality management.