Fire Alarm Trouble Codes and How to React During an Emergency

By Andrew Erickson

November 4, 2023

Fire alarms are crucial for building safety. They act as the first line of defense in a fire by detecting smoke or fire and alerting occupants to evacuate.

However, fire alarms can sometimes show trouble codes that signal maintenance needs. It's essential to understand these codes to ensure the safety of everyone in the building and promptly address any issues.

Fire Alarm Trouble Codes: A Crucial Safety Component

As the individual responsible for fire alarm system maintenance, you're aware of the piercing sound that comes with a fire alarm, which commands immediate attention and action.

Conversely, regarding trouble codes, the response is less about immediate evacuation and more about prompt system troubleshooting and repair.

Trouble codes, unlike alarm codes, indicate issues within the alarm system itself rather than an actual fire or smoke detection.

These problems can vary from malfunctioning smoke detectors to wiring or battery issues. It is crucial to recognize and respond to these codes to ensure the effectiveness of your fire safety measures.

Decoding the Messages: Understanding Your Fire Alarm Panel

Deciphering the language of your fire alarm panel can be challenging. Trouble codes may vary among different fire alarm control panel (FACP) manufacturers, but they all indicate similar underlying issues across systems.

Understanding the specific codes of your panel is worth the effort to ensure a functional and reliable fire alarm system. If you see a "trouble" message, look for its corresponding "restore" message. That restoration message tells you the problem has been resolved, and the system is back to regular operation.

Emergency Preparedness: Responding to Trouble Codes

Before diving into the specifics of each trouble code, let's talk about general preparedness.

When a "Device Missing" alert pops up, it signals a missing component in the system—a detector or sensor malfunctioning or improperly installed. The "Maintenance Required" message reminds you to keep up with routine check-ups to keep your system in top-notch condition.

"Panel Trouble" points to potential issues with the heart of your system, the control panel. And if you see "Supervisory Trouble," you're being alerted to a hitch in the systems monitored by your fire alarm, like sprinkler systems or elevators.

Power-related codes such as "AC Power Trouble", "Low Battery", or "Battery Trouble" are particularly critical, as they indicate your system is on backup power or that your backup power is failing.

Grasping the Basics of Fire Alarm Trouble Codes

Understanding fire alarm trouble codes is crucial for ensuring the effective operation of your fire alarm system.

A "trouble" signal may indicate a system fault, such as a disconnected device or the need for maintenance. Responding promptly to these alerts is essential for maintaining the functionality and safety standards of your establishment.

It's important to note that a "restore" signal often confirms the resolution of a trouble condition, indicating that the problem has been addressed.

Preparing Your Response to Fire Alarm Issues

Having an effective emergency action plan for trouble codes is crucial for the proper functioning of a fire alarm system. It starts with assembling a response team that has a deep understanding of your specific fire alarm system.

Regular drills and comprehensive training ensure that when a trouble code occurs, your team can quickly and efficiently address the issue. The reliability of a fire alarm system depends on the maintenance and attention it receives. You must have a prepared team of experts.

Common Fire Alarm Trouble Codes and Their Meanings

By delving into the individual trouble codes, you can decode the signals from your fire alarm system and take decisive action.

You must understand these common trouble codes to ensure the reliability of your fire alarm system and the safety of your building's occupants.

I've defined these trouble codes at length in previous articles, but here's a quick summary of some common codes and what they mean:

  • "Ground Fault Trouble": This code means there's an unwanted electrical path to the ground, which can cause a part of the fire alarm system to become inoperative. You must locate and correct the ground fault promptly to prevent system failure.
  • "Open Circuit" or "Line Fault": This indicates a break in the continuity of an electrical circuit within the fire alarm system. An open circuit can lead to a failure in sounding alarms or reporting a fire condition. It is important to find and fix any broken wiring or connections immediately.
  • "Communication Trouble": If your system is monitored remotely, this code could indicate a failure in the communication link between your fire alarm system and the monitoring service. Restoring this link is vital to ensure that your system can alert the necessary parties during a fire.
  • "Signal Silence Trouble": This code typically appears when an alarm silence command has been entered, but there is a fault preventing the alarm from silencing. It's essential to identify and resolve the issue to regain complete control over the fire alarm system.
  • "Sensor Trouble": Sensors are the eyes of your fire alarm system. A "Sensor Trouble" code signals that a smoke, heat, or other type of sensor is malfunctioning. Regular cleaning, maintenance, or replacement of sensors is required to fix this issue.
  • "Charger Trouble": This is related to "Battery Charger Trouble" and indicates a failure in the system's ability to charge the backup batteries. The charger ensures battery readiness during power outages. Therefore, it's vital to investigate and rectify this trouble code promptly.
  • "NAC Fault": Stands for "Notification Appliance Circuit Fault," indicating a problem with the circuit that powers devices such as bells, horns, or strobes. A fault like this can stop these devices from working during an alarm, so it's essential to take quick action to fix it.
  • "CPU Trouble": This code indicates a central processing unit (CPU) fault in the fire alarm panel, which can lead to various system malfunctions. CPU troubles often require professional diagnosis and repair due to the complexity of these components.
  • "System Reset Required": Sometimes, the system simply needs a reset to clear a transient condition or to reboot after an error. This code prompts you to perform a system reset, which can often resolve minor issues.

Prompt and informed responses to these trouble codes can mean the difference between a minor maintenance issue and a potential safety hazard. Addressing trouble codes promptly and conducting regular system checks is crucial for prevention.

Understanding fire alarm system trouble codes is not only a regulatory requirement but also a fundamental aspect of proactive safety management in your facility.

After-Action Review and Plan Adjustment

Once the immediate emergency is over, it is crucial to conduct a thorough debriefing. An after-action review allows you to analyze what happened, why, and how it was handled.

This reflective process is essential for learning and improving future responses to trouble codes or emergencies. It is an opportunity to fine-tune your emergency action plan, ensuring that any new insights are integrated and the plan remains effective and practical.

Professional Assistance and Resources

Sometimes, your facility's staff may need help deciphering trouble codes and resolving fire alarm issues. In such cases, it's wise to bring in professionals for assistance.

Additionally, investing in training resources for your staff is beneficial. Making sure they are familiar with emergency protocols can significantly improve the effectiveness of your emergency action plan.

Get Assistance from Digitize

At Digitize, we pride ourselves on having a team of seasoned and highly experienced engineers. As a leading manufacturer of fire alarm monitoring equipment, we leverage this strong expertise to deliver reliable, high-quality, and advanced solutions.

Do you have a question about fire panels, diagnostic/trouble codes, or anything else related to fire alarms? Give us a call now to get answers to your questions.

To speak with Digitize now, call 1-800-523-7232 or email

Andrew Erickson

Andrew Erickson

Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and...Read More