Stop the noise first
- Press Unlock on your key fob first. On Honda and Chevrolet factory alarms, that stops the horn and the flashing lights.
- Use the fob rather than the key in the door, because on some cars the key won't switch the alarm off.
- Then think back to what happened just before it started: a door or the hood opened, someone inside, a window left open, or a battery that went flat.
- Still going off with no clear reason, or Unlock won't stop it? Contact your dealer, or the installer if it's an aftermarket alarm.
When the alarm goes off with nobody near the car, the fob in your pocket is the off switch. We'd press Unlock before trying anything else, since that's how Honda and Chevrolet both tell owners to silence their factory alarms. The metal key doesn't always do it. On a 2015 Chevrolet Tahoe, unlocking the driver's door with the key (opens in a new tab) won't disarm the system or turn off the alarm.
If your car has keyless entry, unlocking a door with the fob on you shuts the alarm off too.
We'd also leave the battery connected. Some cars have a backup siren with its own battery, and on Chevrolets with a battery-backed siren (opens in a new tab), disconnecting the main battery is one of the things that sets it off.
Make sure it's the alarm
A short chirp or beep as you lock up and walk away is the car confirming it's locked. Some cars also chirp or beep when the fob gets left inside. Neither one is the alarm.
The alarm itself keeps going. On a 2025 Honda CR-V, the horn sounds on and off and some exterior lights flash for up to two minutes. On a 2015 Tahoe, the turn signals flash and the horn sounds for about 30 seconds, then the system re-arms.
The panic button on the fob sets off the horn and lights on purpose, and sitting on your keys can press it by accident. On a CR-V, holding it for about a second sounds the horn and flashes some exterior lights for about 30 seconds. Pressing any button on the fob cancels it.
What can set a factory alarm off
Work through these in order. You can check the first few yourself, and the rest need a dealer or installer.
Start with the doors, hood and tailgate. Opening one without unlocking first, while the alarm is set, will trip it. On a CR-V, someone still inside can do it just by unlocking with the lock tab, pulling the hood release or shifting out of Park. To avoid it, don't set the alarm with anyone inside or a window open, and get back in with the fob or keyless entry.
Next, think about movement inside the car. Some cars have interior motion sensors, and an open or partly open window or lightweight items left inside can set them off. Check your car's equipment list to see whether yours has them. If it does, don't arm the alarm with a pet inside either.
Chevrolets with Advanced Theft Deterrent (opens in a new tab) can also have a tilt sensor that reacts when the car is jacked up or towed. With the car off, the ALARM DISABLE button (a car with a line through it) switches off the tilt and interior sensors for the next time the alarm is armed.
Then the 12V battery. On a CR-V, if the battery dies after the alarm is set, the alarm may go off once the battery is recharged or replaced, and unlocking a door with the fob or keyless entry shuts it off. Volvo's technician magazine also lists a weak 12V battery among the reasons an alarm can go off falsely, so mention any recent battery trouble when you book service.
Keep the fob's own battery in mind too, since the fob is your off switch. On a CR-V, a fob whose working range varies probably has a low battery, and if its light doesn't come on when you press a button, the battery is dead. Some cars, like the 2017 Ford Explorer, show a message on the dash when it's low.
Some faults only a technician can confirm. Too much clearance in a hood latch can make its switch report the hood open when it's shut, and Acura's service bulletin (opens in a new tab) for some 2014 to 2016 MDX models names that as the possible cause of alarms that sound on their own. Volvo's technician magazine also lists a broken tailgate harness as a reason an alarm can go off falsely.
If an installer fitted your alarm, take the problem back to them. Directed's Viper 5906V guide (opens in a new tab) says an authorized Directed dealer should make all sensor adjustments to avoid unintended triggers.
If you drive a 2025 Honda CR-V EX
The EX has Smart Entry, so you've got four ways to shut its security alarm (opens in a new tab) off:
- Press Unlock on the fob. One press unlocks the driver's door.
- Grab a front door handle with the fob on you, within about 32 inches (80 cm) of the handle.
- Unlock a door with the built-in key. The keyhole is on the back of the door handle.
- Switch the power mode to ON.
The fob and keyless entry only unlock the doors with the power mode in VEHICLE OFF.
Left alone, the alarm runs for up to two minutes. It goes off when a door, the hood or the tailgate is forced open, not when a door or the tailgate is opened with the key, fob or keyless entry. There's a catch with the key, though. Open a door with it, then open the hood or shift out of P before the power mode is in ON, and the alarm sounds.
The alarm sets itself when the power mode is in VEHICLE OFF, the hood is closed, and all the doors and the tailgate are locked from outside with the fob or keyless entry. The security indicator on the instrument panel blinks, and the blinking changes pace after about 15 seconds. Unlocking with the fob or keyless entry, or switching the power mode to ON, cancels it and turns the indicator off. Glance at that light as you walk away, because it tells you whether the car was armed if the alarm goes off later.
A few other CR-V sounds can pass for the alarm:
| What you hear | What it is | What to do |
|---|---|---|
| The horn on and off with some exterior lights flashing, for up to two minutes | The security alarm | Unlock with the fob, keyless entry or the built-in key, or switch the power mode to ON |
| The horn and some exterior lights for about 30 seconds | Panic mode, after the panic button was pressed for about a second | Press any button on the fob, or switch the power mode to ON |
| A beep as you close up with the fob on you, then flashing lights and another beep once you're about 5 feet (1.5 m) away | Walk Away Auto Lock locking the car. It's off from the factory until someone turns it on. | Nothing. That's the car locking itself. |
| A beep lasting about two seconds after auto lock has started | The auto-lock stop warning, for example when the fob went back inside through a window or into the tailgate, or you're standing too close | Check that you have the fob, then open and close a door and listen for one auto lock beep |
When it keeps going off anyway
If the alarm keeps sounding and nothing above explains it, or unlocking won't shut it off, contact your dealer and have the antitheft system diagnosed. If an installer fitted the alarm, contact the installer.
We'd ask whether they can pull the alarm's trigger history before replacing any parts. In Acura's hood latch bulletin, checking that history is the first diagnostic step, and it shows which switch set the alarm off.
Each time it happens, write down a few details. They give the technician a pattern to work from:
- The date, the time, where the car was parked, how long it went on, whether the horn was on and off, and which lights flashed
- How you locked it, whether the security light was blinking, and how long after locking it started
- Anything just before it went off, like a door or the hood opening, someone inside, a window open or the fob being handled
- Any dashboard message, and what finally stopped it
- Any recent dead battery, recharge or replacement, and any electrical or alarm work
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