8 Common Causes of a DSI Fault Light on RV Water Heater

The days are long gone when you would have to get out of your RV to heat water. DSI, an automated water heating system, has taken over the job. However, the system can sometimes fail, causing the DSI fault light to activate.

Some of the most common causes behind the DSI fault light activation are – no propane in the system, an empty water tank, a clogged burn chamber, and a defective control board. And the easiest solution to fix this issue is to keep the propane tank full and reset the water heater.

A DSI fault light activation is often nothing serious. Read further to know more about the DSI fault light, how it works, and how you can fix any issue within the system.


What Is A DSI Fault Light, And What Does It Indicate?

A DSI Fault light is an indicator that lets you know if there’s a problem with the water heater of your RV. DSI refers to Direct Spark Ignition. The system is responsible for igniting the burner to heat the water. 

Whenever there’s an issue with the water heating system, the DSI flashes a fault code, and the light stays on. The code is known as the DSI fault code, and the light is called DSI fault light or DSI Flt light (Flt means Fault). 

The DSI fault light usually lights up when you turn the water heater on in some RVs. It should go away once the system succeeds in adding flame to the gas and the water starts heating up. 

If the light continues to stay on, there is usually something wrong with the gas flow. However, the fault light will likely go off once you solve the issue.

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Common Causes Of DSI Fault Light Activation

Most of the time, the DSI fault light activation is due to nothing severe, and you can resolve it quickly. 

But before that, you should know the factors that can cause the light to stay on. The seven most common causes of DSI fault light activations are listed below:

  1. Defective control board
  2. The water heater tank is empty 
  3. Faulty ECO circuit
  4. The check valve is occupied 
  5. No airflow; possibility of a leak 
  6. Bad thermostat
  7. Clogged burn chamber 
  8. The system is out of gas

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What To Do When The DSI Fault Light Comes On?

DSI fault light stays on to signal that something is wrong with the water heater of your RV. Let’s check out what you can do to solve this issue.

1. Check the Propane Tank

The first thing you must do is check the propane tank. You may have to refill the tank if it’s out of propane. Also, check the selector switch on the back of the tank. 

2. Check All the Connections

Now go to the back of your vehicle where the water heater is and check all the connections. If you find anything loose, correct it immediately. 

Also, ensure the chambers, wires, and lines are clean and corrosion-free. If you find any faulty element like the thermostat or control board, fix or replace it. 

3. Check the Water Heater Tank and the Valves

You should check the water heater tank and fill it with water if it’s empty. Check all the valves to make sure they are working perfectly.

4. Make Sure No Air is in the System 

If you suspect air in the system, you can run all the stoves at the highest flame for a minute or two to let the air bleed out.

5. Check the Fuse

While at it, locate the fuse designated for the water heater and check if it’s working fine. 

6. Let the DSI Completes its Three Cycles and Reset the Water Heater

When the DSI tries but fails to ignite the burner, it tries to light the propane three times. Before resetting the water heater, you must wait for the DSI to complete this ritual. 

You can tell by just paying attention to the system’s clicking sound every time the DSI attempts to light the propane up. If it doesn’t work, you can try resetting the water heater.  

In most RVs, you can find the button outside on the WH panel. If you can’t detect the reset button, you can always take help from the user’s guide. 

As you detect the button, press it to reset the water heater. Wait for the system to readjust and heat the water successfully.

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Tips For Preventing Future DSI Fault Light Activations

Since the DSI fault light is a part of a safety mechanism to safeguard the system against trouble, there are no specific preventive measures. Nonetheless, the following tips might help you in the long run.

1. Perform Regular Maintenance

Regular maintenance is the key to keeping the water heater of your RV running in good health for a long time. 

2. Keep the Water Heater Clean and Free of Rust

It would help if you kept the water heater and any wire leading in and out of the system clean and free from rust. 

3. Drain and Flush the Water Tank from Time to Time 

It is a good practice to drain and flush the water tank from time to time. This simple step will ensure the tank stays clean and free from residue and mineral deposits. 

4. Check the Water Tank and Gas Supply before Going on the Road 

Before you set off for a journey or an adventure with your RV, ensure that the water tank and gas tank are adequately filled.

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Now that you know all about the DSI fault light and how it works, let’s check out some frequently asked questions by users and RV enthusiasts.

How long will it take for the water to get hot after resetting?

Usually, it takes around 30-40 minutes for a gas water heater and approximately 1-1.5 hours for an electric water heater. As you reset the water heater, you will have to give it time to readjust and start heating the water again. 

What causes the reset button to trip? 

Sometimes, the reset button of your water heater continues to trip. This usually happens when the water gets too hot, causing the ECO to trip frequently. There may be something wrong with the heater that you need to address. 

Is emptying the water heater tank of your RV necessary after each trip?

It may be beneficial for the system if you drain the tank after every trip (unless another one is planned in the next 15 days). It can help to clear away any deposits so you can get fresh hot water the next time you use the water heater. 

Is it safe to keep the water heater in your RV on all the time?

Safety is not the issue here. Like we do at home, there should be no issue keeping the water heater in your RV on all the time. However, this can become an issue due to the expense and unnecessary fuel consumption. 


If you own an RV, you should know both the perks and inconveniences that come with this vehicle. However, modern-day RVs offer fantastic upgrades to improve the user’s experience.

Most new RVs come with the convenience of getting hot water from the inside, thanks to the DSI system, a luxury you could only enjoy indoors. The DSI fault system is designed to keep the water heating system and the vehicle safe from any hazardous situation.

When the DSI fault light refuses to go off, the best way to resolve the issue is by checking the propane tank and filling it up correctly. However, if none of the solutions help your situation, take a professional’s assistance as there might be something wrong that needs an expert opinion.

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