Dear customer, there are several factors that cause this inconvenience, what happens is that the alarm system is controlled by a module, which is responsible for controlling not only the alarm but also the central locking system and even the anti-theft system.
This module can be deconfigured by various factors either by a defective battery by a defective key fob, by a defective battery of the key fob due to configuration problems in the vehicle.
The steps to arrive at the solution of these problems are progressive. So first you have to ruleo out the battery of the key fob, it is the first thing you must do to observe that it is not a bad signal emitted from the control. Although it works correctly with the vehicle it may be problems with its signal set correctly due to low battery voltage.
Then the control must be programmed again with the anti-theft system. But if the fob does not take programming or even after programming the problem continues, they must replace the control.
And finally, if the problem continues once replacing the fob, we will be sure that the module has problems and that it must be replaced. But this is very unlikely to happen, the most common is that the controls are subjected to certain shocks, humidities, etc., What can cause them to stop working one moment at another.