How to Fix Generac Error Code 1603: Underspeed

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Imagine this: You are enjoying a cozy evening at home with your family when suddenly the lights go out. You hear thunder and see flashes of lightning outside. A storm has knocked down the power lines in your area, and you don’t know how long it will take to restore the electricity.

Luckily, you have a Generac generator that can keep your essential appliances and devices running until the power comes back on. You go outside to start the generator, but instead of hearing the familiar hum of the engine, you see a flashing red light on the control panel. It says, “Error code 1603: under speed.”.

What does that mean? How can you fix it? And how can you prevent it from happening again?

If you own a Generac generator, you may have encountered this error code at some point. It is one of the most common issues that affect Generac generators, and it can be frustrating and inconvenient.

But don’t worry; we are here to help. In this blog post, we will explain what error code 1603 means, what causes it, how to troubleshoot it, and how to avoid it in the future.

What Caused the Generac Error Code 1603?

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Error code 1603 can be caused by several factors, such as:

1. Fuel supply issues

If the generator is running on propane or natural gas, there may be a problem with the fuel pressure, regulator, valve, or tank.

For example, if the propane tank is low or frozen, the fuel flow may be insufficient or interrupted, resulting in underspeed.

Similarly, if the natural gas line is clogged, damaged, or leaking, the fuel supply may be compromised.

2. Overload issues

If the generator is overloaded, meaning that it is supplying more power than its rated capacity, it may struggle to maintain the required speed and frequency.

This can happen if the generator is connected to too many appliances or devices or if there are sudden surges or spikes in the power demand.

3. Speed control issues

If the generator’s speed control system, which consists of the governor, throttle, and sensors, is malfunctioning, it may not be able to regulate the speed and frequency of the generator.

This can happen if the speed control components are dirty, worn, or damaged, or if the settings are incorrect or out of calibration.

RECOMMENDED READ:- How to Fix Generator Overspeed in 4 Simple Ways

How do I troubleshoot the Generac Error Code 1603?

If you encounter error code 1603 on your Generac generator, you can try the following steps to troubleshoot and fix it:

1. Check the fuel supply.

Make sure that the fuel tank is full and not frozen, and that the fuel pressure and flow are adequate and consistent.

If you are using propane, you may need to switch to a larger tank or use a tank heater to prevent freezing.

If you are using natural gas, you may need to check the gas line for any blockages, leaks, or damage and contact your gas provider if necessary.

2. Check the load.

Make sure that the generator is not overloaded and that the power demand is within its rated capacity.

You may need to reduce the number of appliances or devices connected to the generator or use a transfer switch to isolate the essential loads.

You may also need to check the wiring and connections of the generator for any short circuits, loose connections, or corrosion, and replace or repair them if needed.

3. Check the speed control.

Make sure that the speed control system is working properly and that the governor, throttle, and sensors are clean and in good condition.

You may need to adjust or recalibrate the speed control settings according to the manufacturer’s instructions by checking your manual comment on your generator model below or replacing any faulty or damaged components.

RECOMMENDED READ:- Generac Fault Codes: What Are They?

How do I prevent the Generac Error Code 1603?

To prevent error code 1603 from occurring again, you should follow these tips:

1. Maintain the fuel supply.

Keep the fuel tank full and protected from freezing, and monitor the fuel pressure and flow regularly.

If you are using propane, use a larger tank or a tank heater, and if you are using natural gas, inspect the gas line periodically for any issues.

2. Maintain the load.

Keep the load within the generator’s rated capacity, and use a transfer switch to manage the power distribution.

Avoid connecting too many appliances or devices to the generator, and avoid sudden changes or fluctuations in the power demand.

3. Maintain the speed control.

Keep the speed control system in optimal condition, and follow the manufacturer’s recommendations for the speed control settings. Clean and inspect the speed control components regularly, and replace or repair them if necessary.

RECOMMENDED READ:- How Often Should You Service a Generac Generator?

Final Words

Generac error code 1603 is a common error that indicates an underspeed condition, which can affect the generator’s performance and output.

This problem can be caused by fuel supply issues, overload issues, or speed control issues, as explained above. To fix it, you need to check and troubleshoot these factors, and to prevent it, you need to maintain them properly.

By following these steps, you can ensure that your Generac generator runs smoothly and reliably and provides you with the power you need. If you have any questions or comments, please feel free to leave them below.


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