Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Air Quality Sensor (AQS) (Only ECC)
The air quality sensor (AQS) is, together with a particle filter and the humidity filter, part of a system which has the role of ensuring that the air in the passenger compartment is free of pollutants. The role of the air quality sensor (AQS) is to transmit a signal to the climate control module (CCM) if it detects increased concentrations of pollutants in the outside air.
The air quality sensor (AQS) measures concentrations of COx and NOx.
The climate control module (CCM) uses the signal to control the recirculation damper motor.
The air quality sensor (AQS) compares the present values with previous ones and can calculate changes in pollutant concentrations.
The Air quality sensor (AQS) is directly connected to the climate control module (CCM).
The signal from the air quality sensor (AQS) to the climate control module (CCM) has four steps, 0-3:
- signal 0 = no increase in or reduced pollutant level
- signal 1 = gradual increase in pollutant level
- signal 2 = medium increase in pollutant level
- signal 3 = rapid increase in pollutant level.
The air quality sensor (AQS) is under the cowl on the right-hand side of the fresh air intake.
There are diagnostics for the air quality sensor (AQS).
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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