Fire Alarm Flashing But No Sound: Causes & Solutions

The fire alarm is flashing and not making any sound due to technical issues in the alarm system. It can be that the battery is low or there is any internal malfunction. The reasons can also be related to dust accumulating over the sensor or the smoke detector not getting enough power to start. 

Check how long the fire alarm flashes because that is significant in how you are going to solve this problem. To get a further idea on fire alarms and when to replace them, keep reading this article. 

Why Is The Fire Alarm Flashing Red Without Any Sound?

The fire alarm will flash red lights without any sound if there is any problem with its internal system. Almost all fire alarm brands have a blinking LED light to show its activation. It also uses this LED light to give warnings regarding device issues.

It’s a feature that’s shared by almost all fire alarms independent of their manufacturer. Depending on the time interval of the light flashing, you can figure out the hidden meaning.

The table below shows some of the common reasons why the fire alarm will flash red light based on different time intervals. 


Fire Alarm Flashing Red Light Time Interval


5 – 8 seconds

Low Battery

10 seconds

Internal Malfunction

15 seconds Needs Battery Replacement
30 – 60 seconds

Working Just Fine

Now, let’s discuss each scenario in detail.

Scenario-1: Fire Alarm Flashing Red Every 5 Or 8 Seconds

A Fire alarm flashes red every 5 seconds or 8 seconds refers to low battery power. Some fire alarm makes a chirping sound rather than beeping when it’s running on low battery.

Most fire alarms are powered by a 9V battery. These batteries only last around 6 months. Check the battery expiration date and replace it if needed. 

If the fire alarm is lithium powered then there’s no need to change the battery. But look for any loose connection in the wires.

Fire alarms like these need to be replaced after 10 years. The same goes for any alarm that’s hardwired into your house’s electric system. 

After 10 years of use, fire alarms cross their expiration date. However, make sure to replace the battery every 6 months. 

Scenario-2: Fire Alarm Flashing Red Every 10 Seconds

When your fire alarm blinks red at 10-second intervals, it primarily indicates an internal malfunction. But depending on the fire alarm model the reason could be different.

In some fire alarm models, this indicates the alarm is temporarily in a desensitized state. It could also refer to low battery. As for internal malfunction, the wirings and the internal components have to be checked.

In short, it needs to be inspected. The inspection cost of a fire alarm isn’t much. Also, it’s a much-needed procedure for any establishment.

You can contact your local fire department to conduct a fire alarm inspection.

Scenario-3: Fire Alarm Flashing Red Every 15 Seconds

A fire alarm flashing a red light every 15 seconds means the battery needs replacement. It doesn’t simply mean that the battery is low rather it is in bad shape.

Without the battery, your fire alarm unit won’t work properly. So, replace it as soon as possible. Also, test the smoke detector batteries from time to time for corrosion.

Scenario-4: Fire Alarm Flashing Red Every 30 to 60 Seconds

Your fire alarm flashing red LED once every 30-60 seconds is very normal. Generally, it means the detector’s alert has been activated and working properly.


Fire Alarm Flashing Red

It could blink right after 30 seconds 45 seconds or 60 seconds even. But some fire alarms indicate just the opposite. To be more sure you can check the user manual.

Scenario-5: Fire Alarm Flashing Red & Green

Flashing both red and green lights means there’s a problem with the fire alarm battery. Either it’s running on low battery or it needs to be replaced. 

Read the user manual to be more sure about your fire alarm. A solid red light indicates that the batteries are low on power. Similarly, a blinking green light could mean the same thing.

But a solid green light means the alarm is working just fine. To be more specific, the alarm is receiving power from an AC outlet and thus working properly.

Scenario-6: Fire Alarm Flashing Red After Changing Battery

If the fire alarm flashes a red light after changing the battery it could mean improper installation. Check if you have installed it upside-down. 

Also, check if you’ve pushed the battery to its compartment or not. Removing and reinstalling the battery might solve the issue. 

If it still blinks after reinserting, then it could be an internal malfunction. In the case of hard-wired fire alarms, the issue can be in the electrical system as well.

Bonus: Find out more about the methods of fire prevention

Other Reasons For Fire Alarm Flashing Red With No Sound

Normally a fire alarm will blink red without making any sound if there is dust in its sensors or if the smoke detectors are not receiving enough power.

Let’s discuss them in detail.  


Fire alarms work with sensors that detect the heat, flame, or gas in the air. Which means it’s always open to the air and dust. With time, dust, debris, and insects get into the alarm compartment and clog it.

This may block the sensors from doing their job. The fire alarms often give you a warning through the flashing red light. Some fire alarm models have this feature integrated into them. Yours might be one of them. Dust is one of the reasons why false alarm happens.

Smoke Detector Not Receiving Power:

Smoke alarms have two power sources. One is the building power supply and another is the alarm’s backup battery. When a power outage happens, the battery powers the alarms.

The lack of receiving power can be a reason why it’s flashing red light. It can be an electrical fault like loose wiring as well. It’s better to get your fire unit tested by a technician in this case.

Smoke Detector Flashing Red Light

Needs Replacement:

If your fire alarm keeps flashing a red light unusually it might have gone broken. Or, it may need an upgrade.

Fire alarms can last about 10 years. After that, they pass the expiration date and fail to perform properly. So if your fire alarm is 10 years old, it’s time to get a new replacement.

When To Be Concerned About Smoke Detector Flashing Red Light?

If the fire alarm’s red light is on all the time or the red light keeps blinking with a beeping sound then you need to be concerned and take action immediately.

Before that, you need to understand the reasons for each of these cases. 

Scenario-1: Red Light Is On All The Time

You should be concerned if the alarm’s red LED light is always on. If it’s in a stable or stagnant position it indicates that the sensor has detected smoke. 

Unless you reset the alarm again it will not make any sound. So, in case, the sensor senses smoke again it’ll not notify you.


To reset your fire alarm, first turn off the power of the circuit breaker. Dismount the fire alarm and unplug all the connections. Now, remove the battery.

There’ll be a TEST or RESET button in your smoke detector. Press and hold it for 15-30 seconds. Keep the button pressed until the LED indicator flashes again.

Now reconnect the wires and put the alarm back in its position. If the problem is not solved, consult a technician.

Scenario-2: Red Light Blinking With Beeping Sound

Your fire alarm blinking red might not indicate any serious issue. But if it comes along with a beeping sound then it indicates a serious problem. 

The blinking red light followed by a beeping sound means the detector senses smoke. Thus it’s responding to the smoke alert or the batteries are about to die. 


Safety comes first, so think of evacuation if the situation seems to be an emergency. If it turns out to be a false alert, then get the system checked by a technician.

Fire Alarm Flashing Red With No Sound

Frequently Asked Questions (FAQs):

Why is my smoke detector flashing red after going off?

The smoke detector flashes red light after going off indicating the presence of lingering smoke. There might be still some smoke left in the sensor compartment. Some smoke detectors blink red light when the smoke is still clearing.

How do you install a smoke detector?

To install a smoke detector, first mark some drill points on the ceiling. The drill points should be at least 8 inches away from the nearest wall. Drill holes on the marked points and mount the smoke detector on the mounting bracket. You’ve to twist the detector so it engages the bracket.

Why is my smoke detector beeping every 30 seconds?

Smoke detectors can beep every 30 seconds for a few reasons. It could mean the device is running on low battery. It can also be that the battery is installed in the wrong direction. You can try reinserting the battery. Also, make sure it’s settled in the compartment.


A fire alarm flashing but no sound doesn’t refer to any serious problem. However, you should not ignore it. Small problems can also create a bigger mess.

Also, ensuring the fire alarm functionalities is very important. Hopefully, the discussion was able to aid you in this respect.

Stay happy stay safe!