Generac Generator Turns on Randomly (Cause & Solution)

Generac generators are renowned for their reliability and efficiency in supplying power during blackouts. These power generators have robust designs that ensure a steady power supply when the grid is down. But what happens when your Generac generator starts acting up, powering on randomly, without any apparent reason? In this article, we will find the cause and solution of this odd behavior and suggests potential solutions.

Understanding the Functions of a Generac Generator

Typically, a Generac generator should function smoothly once set up correctly, providing backup power when there’s a power outage. These units come with both automatic and manual modes, allowing you to decide when they should start running. Like any other machine, regular maintenance is key to ensuring your generator functions as expected.

Do Generac generators turn on automatically?

Yes, Generac generators can turn on automatically. One of the key features of Generac standby generators is their ability to automatically start in the event of a power outage. This is made possible by an Automatic Transfer Switch (ATS), which monitors the electrical supply from your utility.

When the ATS detects a power outage, it signals the generator to start. Once the generator is running and producing electricity, the ATS then switches the electrical load from the utility to the generator. This ensures that your home or business continues to have power, even during an outage.

In addition, Generac generators also have an ‘Exercise’ mode where they automatically run for a short period (usually around 20 minutes) every week to ensure they remain in good working condition. This operation can also give the appearance of the generator starting up randomly, but it’s a normal part of the generator’s maintenance process.

Please note that these features are usually available in standby or fixed generators and may not be present in portable models.

generac generator start randomly

Identifying Possible Reasons for Random Startup

Before diving into the possible solutions, let’s unravel the possible reasons why your Generac generator might turn on randomly:

  1. ‘Exercise’ Mode: Generac generators have an ‘Exercise’ mode that lets them run for a short period, typically 20 minutes, every week to keep the components in good working condition.
  2. Automatic Transfer Switch (ATS): The ATS is designed to sense when the utility power goes out, causing the generator to start. Any malfunction here could cause the generator to start randomly.
  3. Power Fluctuations: Sometimes, power variations or unstable power supply could trigger the generator to start thinking there’s a power outage.
  4. Firmware/Software Issues: Outdated or faulty firmware/software could cause a generator to behave erratically.
  5. Environmental Factors: Elements such as moisture, pests, or extreme temperatures might also cause a generator to start unexpectedly.

Diagnostic Steps to Understand Why Your Generac Generator Turns on Randomly

After identifying potential causes, here’s how you can diagnose the problem:

  1. Regular Maintenance Checks: Ensure that the generator’s components are in good working condition.
  2. Check for Error Codes: Generac generators display error codes for certain problems. Check for these codes on your generator’s control panel.
  3. Test the Automatic Transfer Switch: Inspect the ATS for any possible malfunctioning.
  4. Monitor Power Fluctuations: Keep an eye on your home’s power stability.
  5. Check Firmware/Software: Ensure that the generator’s software is up to date.

Solutions to Fix the Random Startup Issue

Now, let’s discuss how to fix this issue:

  1. Adjust the ‘Exercise’ Mode Settings: Ensure that the ‘Exercise’ mode is properly set up, and the generator is not mistaking it for a power outage.
  2. Service the Automatic Transfer Switch: If the ATS is malfunctioning, it might need to be repaired or replaced.
  3. Install Power Stabilizers: To regulate your home’s power supply, consider installing power stabilizers.
  4. Update Firmware/Software: Keep your generator’s software updated to avoid any software-related issues.
  5. Professional Assistance: If you can’t pinpoint or solve the problem, it’s best to call for professional help.

Tips for Preventing Future Random Startups

Prevention is better than cure. Regular maintenance, keeping the generator’s software updated, and proper handling can help prevent such issues. Don’t underestimate the value of professional inspection and servicing, especially if you’re not mechanically inclined.


In conclusion, a Generac generator turning on randomly can be disconcerting. However, with the right knowledge and diagnostic steps, you can identify and rectify this issue. Regular maintenance, timely upgrades, and professional servicing are vital to ensure your generator runs smoothly when you need it the most.

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Rayan is an engineer, lives in a farmhouse. He has a passion for electronics and alternative energy. He loves to share his thoughts with other people. That is why he started the blog.

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