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. 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 upper electronic module (UEM) which activates the alarm.
Mass movement sensors (MMS) are located in the ceiling, in the center of the vehicle, to optimally cover as much as possible of the vehicle's volume.
The mass movement sensor module (MMS) is powered from the upper electronic module (UEM) and earthed in the body.
There are diagnostics for the mass movement sensor module (MMS).
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.