After a few break-ins in my neighborhood, someone suggested that we all sleep with the keys to our cars next to our bed. That way, if we hear a burglary in process we can use our car alarm to summon help. The myth busters at Snopes investigated this technique and pointed out that unless your car alarm is an agreed-upon signal, it’s unlikely it will motivate your neighbors to call 911. Calling the authorities yourself should be your first priority.

Can you set off your car alarm from your house?

According to Volvo, a car key fob remote’s range is approximately 65 feet. Walls and other obstacles can inhibit this signal and shorten your remote’s range. If you plan on using your car alarm in an emergency situation, make certain to test it first.

Snopes points out that your ideas for home defense are not a plan until you have tested and practiced them. If you are considering using your car alarm as a deterrent or signal during a home invasion, first test whether you can activate it from your house.

Remember, any trees near your house may slow your key fob’s signal more during seasons when they are covered in leaves. Certain aftermarket car alarms have a longer range. In addition, some car owners claim that holding their key fob remote beneath their chin increases its range because their skull acts as a repeater. Again, test this method before relying on it in an emergency situation.

Will a car alarm stop a burglar?

If a burglar is looking for an empty house to rob, setting off your car alarm may deter them. But there are easier ways to signal that you are home. In an especially crowded area, someone planning a more violent break-in may get skittish about the added attention, but this is not guaranteed.

According to Snopes, “The typical burglar looks to rob domiciles where no one is home.” But in this case, setting off your car alarm may be overkill. Simply flipping on a light makes it clear that someone is home. Hopefully, this will convince the typical burglar that your home is not worth the effort.

Snopes adds that if you flip on a light and then continue to hear or see someone breaking in, it’s time to call for help. At this point, you should dial 911 immediately.

Will a car alarm summon help?

Unfortunately, false car alarms are common enough that setting yours off will rarely summon well-meaning neighbors. People are used to curious animals and jostling setting off car alarms, they rarely come running when they hear one.

In an unfortunate 2003 incident, a burglar broke into a Montreal home and the neighbors ignored the home alarm, assuming it was a faulty car alarm. One neighbor admitted, “We all heard the alarm go off but you get desensitized to alarms. I thought it was a car alarm. I said to my daughter ‘I’m going to close the window because that car alarm is bothering me.’”

If you and your neighbors have agreed that a car alarm is a signal for a home invasion, it might be worthwhile to set yours off–while calling 911. But if you haven’t had these conversations, setting off your car alarm during a home invasion is unlikely to accomplish much.

Learn a retired Navy SEAL’s tips for preventing and surviving a home invasion in the video below: