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Marty, Bosch Certified Master Technician
Category: Car
Satisfied Customers: 54840
Experience:  Bosch Certified Master Technician with over 35 years experience in the automotive industry.
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mercedes S320 car :- car alarm goes off intermittently when

Customer Question

mercedes S320 car :- car alarm goes off intermittently when car parked overnight. all doors have been locked. What is the fault?
Submitted: 4 years ago.
Category: Car
Expert:  Marty replied 4 years ago.
Hi, and welcome. My name is Marty. Intermittent alarm faults on this model are almost always caused by a faulty alarm siren. When the back up battery in the siren begins to fail it will cause this problem. You will need to get your car connected to the Mercedes Star Diagnosis tester to read out the fault memory in the anti theft alarm system. More than likely there will be fault codes stored for a faulty alarm siren. The battery in the siren is not replaceable. If you have fault codes stored for the siren you will need to replace the siren. There are some other possibilities for intermittent alarm activation but the fault codes will point to the specific problem.

Please let me know if you have any questions.