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Radiator Flap On-The-Fly

Radiator Flap On-The-Fly

Owned by Szymon
Last updated: Mar 17, 2025 by Alex Iwan
2 min read

Controls are available on G-Series vehicles with Radiator Flaps installed from factory

The MG Flasher app includes a feature that allows users to manually control the radiator flaps in G-Chassis BMW’s. This function provides enhanced cooling management, making it a valuable tool for performance enthusiasts and those looking to optimize their engine’s thermal efficiency.

Radiator flaps are automatically opened when Max Cooling is enabled or Anti Lag is active. In-app Custom Code diagnostic menu can also be used to Open, Close, or set OEM control of the flaps until the ECU is reset or goes to sleep (the value is NOT stored in EEPROM).

There is no ability to control the Radiator Flap using the Custom Code Menu (CCM) at this time.

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How to Use

  1. Connect to Your Vehicle - Use your OBD device and launch the MG Flasher app.

  2. Navigate to the diagnostic section- In the app, find the ‘Radiator Flaps’ control icons in the diagnostic menu. 

  3. Adjust Settings - Choose to manually open or close the radiator flaps based on your needs.

  4. Monitor Performance - Use real-time data logs to assess how manual flap control affects your car’s cooling efficiency and performance.

  5. Through OTS Map - Use the custom options menu to enable max cooling and/or anti-lag. The radiator flaps will automatically operate in the most efficient manner when either of these features are active.

 

Benefits of Manual Radiator Flap Control

  1. Improved Cooling Efficiency - Manually opening the radiator flaps increases airflow to the radiator, helping to lower engine temperatures, especially under high-performance conditions.

  2. Enhanced Performance in Extreme Conditions - Keeping the radiator flaps open can be useful during track days or spirited driving to ensure maximum cooling.

  3. Reduced Heat Soak - By controlling the flaps, users can minimize heat buildup in the engine bay, reducing power loss due to excessive temperatures.

 

Supported Vehicles

This feature is available for the following BMW models using the MG Flasher app:

  • BMW G20 3 Series (2019+)

  • BMW G22/G23 4 Series (2020+)

  • BMW G30 5 Series (2017+)

  • Other G-Chassis models with electronically controlled radiator flaps

 

Important Notes

Default Behavior - By default, BMW's ECU manages the radiator flaps for optimal efficiency. Manual control should only be used when necessary.

 

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