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.
Mass Movement Sensor Module (MMS)
The mass movement sensor module (MMS) detects movements inside the passenger compartment using high frequency radio waves of 2.45 GHz. The Doppler effect principle is used to determine whether the frequency of the received microwave is different from the transmitted microwave. If the frequency has changed, this is interpreted as a movement in the vehicle. If a movement is detected, a trigger signal is transmitted to the central electronic module (CEM) which activates the alarm.
The mass movement sensor (MMS) is in the headlining in the center of the vehicle. This ensures optimum coverage of the interior of the vehicle. There are two sensors in five door cars. One is positioned in the center of the roof and the other in the roof above the cargo compartment.
There are diagnostics for the mass movement sensor module (MMS).
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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.