Air Quality Sensor / Smog Sensor (Climatronic Air Conditioning System) – 4H0907658A

Original electronic outdoor air quality sensor (Air Quality Sensor / G238 pollution and smog sensor), designed for Audi A7 Sportback (4K / 4K8 generation) and Audi A6 (C8 / 4K generation) cars, as well as other VAG Group models on the MLBevo and MQB platforms.

Original VAG Group automatic air conditioning system (Climatronic) component. It is responsible for continuously monitoring the concentration of harmful substances in the air drawn into the cabin (nitrogen oxides, carbon monoxide, and exhaust hydrocarbons). If pollutants are detected, it automatically sends a signal to the air conditioning control unit to immediately close the fresh air flap and switch to recirculation mode (closed-loop operation).

Technical specifications:

• OE part number: 4H0907658A / 4H0 907 658 A (interchangeable with series numbers 4H0907658, 4B0907659, 8K0907659)

• Function: Air quality sensor / automatic closed-loop sensor (Air Quality Sensor G238)

• Control: LIN-Bus digital bus (3-pin connector)

• Mounting side: Front – cowl / fresh air intake duct to the blower

• Steering wheel side: Left (LHD – European version) and Right (RHD)

• Condition: Original used part (100% functional, tested for communication with the air conditioning control unit – no DTC errors / no G238 sensor damage error, intact housing, clean measuring membrane, straight and rust-free pins in the connector)

• Manufacturer: Audi / VAG (Original OEM)

Main applications:

• Audi:

  • A7 Sportback (4K8) – model years 2018 to 2024

  • S7 / RS7 Sportback (4K8) – model years 2019 to 2024

  • A6 Saloon / Avant / Allroad (C8 / 4K2 / 4K5) – model years 2018 to 2024

  • S6 / RS6 Avant (C8 / 4K8) – model years 2019 to 2024

  • A8 / S8 (D5 / 4N and D4 / 4H) – model years 2010 to 2024

  • Q7 / SQ7 / Q8 / SQ8 / RS Q8 (4M / 4MN) – model years 2015 to 2024

  • A4 / S4 / RS4 (B9 / 8W) and A5 / S5 / RS5 (F5)

• Volkswagen / Porsche / Skoda / Seat:

  • Selected models with Climatronic automatic air conditioning

Fitment guarantee and VIN verification

Each sensor undergoes diagnostics to check the correctness of readings on the data bus and the functionality of the semiconductor element.

Installation note: The sensor is mounted in the air intake housing in the cowl. Its damage is indicated by the lack of automatic switching to internal circulation behind vehicles emitting exhaust fumes and a permanent air quality sensor error in the air conditioning control unit (address 08). Before purchase, we recommend comparing the OE designation on the old part or verifying it using the vehicle's VIN.