Where is the Audi Air Humidity Sensor Located?
3 Answers
Audi air humidity sensor is located beneath the rain sensor, adjacent to it. Additional information is as follows: 1. Classification: Based on their functions, sensors can be categorized into those measuring temperature, pressure, flow rate, position, gas concentration, speed, light intensity, humidity, distance, etc. Each serves a specific purpose, and if any sensor malfunctions, the corresponding device may operate abnormally or cease functioning altogether. 2. Composition: The intake air temperature sensor primarily consists of a plastic housing, waterproof socket, gasket, thermistor, etc. It employs a negative temperature coefficient thermistor as the sensing element. To ensure accurate measurement of intake air temperature, a plastic housing is often used for protection, preventing the installation location's temperature from affecting the sensor's operational precision. 3. Working Principle: The intake air temperature sensor is a negative temperature coefficient thermistor. Its working principle is that as temperature increases, resistance decreases, and as temperature decreases, resistance increases. The variation in resistance within the circuit leads to voltage changes, thereby generating different voltage signals to facilitate automatic operations of the control system. During cold starts, the signal from the intake air temperature sensor is similar to that of the engine coolant temperature sensor. During warm operation, its signal voltage is approximately 2~3 times that of the coolant temperature sensor.
I was also curious about this issue before. A friend who drives an Audi told me that the humidity sensor is usually hidden inside the black cover at the base of the interior rearview mirror. Last time, I specifically opened the mirror cover of my old A6 and indeed found a small box about the size of a matchbox with ventilation slots. The mechanic said that was the humidity probe. This device works alongside the rain sensor, specifically monitoring the cabin humidity and transmitting data to the automatic air conditioning system. Later, when I went for maintenance on a new Q5, I noticed the location was different—it was actually inside the air intake vent along the top edge of the windshield. The positions do vary across different Audi models, but the basic principle is that it needs to be placed in an area with air circulation for accurate sensing. If you want to find it yourself, I recommend checking the repair manual first or using a flashlight to carefully inspect around the rearview mirror for any small hole arrays.
My A4 just had this part replaced at the 4S dealership. The technician pointed to the back of the rearview mirror and explained: The air humidity sensor is most likely mounted along the upper edge of the windshield right in front of the cockpit. That area houses the entire environmental sensing system, where three sensors—rain, light, and humidity—are packed into a space the size of a fingernail, working in sync. The sensor surface is covered with micron-sized openings that continuously capture air moisture data and transmit it to the climate control module. I remember one summer during a heavy rainstorm when the windows fogged up, it was this sensor that triggered the AC's dehumidification mode. The technician advised against attempting to remove this delicate component yourself, as it's tucked away in a hidden spot with fragile wiring, and improper removal could damage the control board linked to the wiper function.
