Mr Heater Big Maxx Problems [How To Fix]

The most common Mr heater big Maxx problems are that it has no power, it won’t ignite, the fan keeps running, pressure switch problems, and circuit board problems.

Keep reading this Mr heater big Maxx troubleshooting guide to learn more about these problems. We’ll also explain the steps you should take to solve these problems and share what all the error codes mean. Let’s jump right in!

Table of Contents

Mr Heater Big Maxx Problems [5 Easy Fixes]

We’ll discuss the most common Mr heater big Maxx issues in detail.

1. Mr Heater Big Maxx Has No Power

The most common reasons why there is no power on the Mr Big Heater are:

  • Faulty power outlet or wiring in the house.
  • Tripped circuit breakers.
  • Wrong setting in the thermostat.


To test out the power outlet and wiring of the house, use another electronic appliance in the same power outlet. If it works, that means your power outlet is fine. Otherwise, it’s best to replace it.

Check if the circuit breakers are tripped. Heaters require a lot of power and can cause the circuit breakers to be tripped. Reset it or change it altogether if this happens.

Mr Heater only works if the temperature of the thermostat is higher than your room temperature. Increase the temperature in the thermostat or wait for your room to cool down for the Heater to turn on.

2. Mr Heater Big Maxx Not Igniting

The most common reasons behind your Mr. heater Big Maxx igniter not working are:

  • There is a blockage in the exhaust pipe.
  • The flame sensor is faulty.
  • The vacuum hose beside the rotor fan is clogged.


Check the exhaust pipe and see if there is any blockage in it. Use a vacuum cleaner to remove the blockage in the exhaust pipe if there is any.

Clean the flame sensor using a sand cloth. You need some expertise to open up the heater and put it back without damaging any components. Don’t tackle this on your own if you’re not feeling confident.

The metal cabinet of the hose has to be cleaned with a wire twister or another sharp object. Keep blowing air to the hose and see if the pressure switch is working. The heater should turn on if there are no other issues.

3. Mr Heater Big Maxx Fan Keeps Running

There can be several reasons that cause the Mr Heater fan to keep running constantly. The most common issues that keep the fan running are:

  • A blocked or obstructed flue.
  • Faulty fan limit switch.


You’ll get the smell of smoke if there is an issue with the flue. It blocks the pressure switch and causes the fan to keep running. You have to clean the flue to get rid of this problem.

The limit switch causes the fan to turn on and off when the thermostat reaches the desired temperature. You need to replace the limit switch if this is the case.

4. Mr Heater Big Maxx Pressure Switch Problems

Mr Heater won’t ignite if the pressure switch is open or closed. This issue is indicated by 3 slow flashes from the LED light on the control board. The problem can be caused by:

  • Clogged vacuum hose.
  • Faulty rotor fan or rotor blades.
  • The area isn’t well-ventilated.


A clogged vacuum hose is an issue that can cause several problems in Mr Heater. We’ve already discussed how you can clean the metal cabinet and the hose if this happens. You’ll have to replace the rotor blades and get a new rotor fan if they’re faulty.

Clean the heater and remove any cocoons or cobwebs that may have formed.  

If the area isn’t well-ventilated, it will block the supply of oxygen to the burner. So, you need to keep the heater in an area that has a sufficient air supply to ensure the proper supply of oxygen.

5. Mr Heater Big Maxx Circuit Board Problems

The circuit board problems in Mr Heater are generally caused by faulty wiring. The wiring becomes loose with the passage of time as the heater keeps vibrating when it’s operational.

That causes the circuit board to fail. Clogged air filters in the heater can also lead to a faulty circuit board.


If the wiring is messed up, calling in a technician would be the best thing to do. Before you do that, clean the air filter or replace it to be sure that it’s the wiring that causes the issue.

Mr Heater Big Maxx Error Codes

Here are the LED codes that will help you to figure out what’s wrong with your Mr Heater.  These codes are usually available on the back of the cover:

Slow Flash: It means that the operation is normal and the flame sensor isn’t calling for heat.

Fast Flash: Normal operation and the flame sensor is calling for heat.

2 Flashes: This means system lockout and the heater is failing to detect and sustain the flame. Ensure you have a proper gas supply and that the flame sensor and igniter are okay if you face this issue.

3 Flashes: 3 Flashes indicate the pressure switch is either open or closed. This is the most common issue with a Mr Heater Big Maxx heater. Cleaning the pressure sensor hose will solve this problem in most cases.

4 Flashes: This indicates a high limit or the rollout switch is opened. A faulty blower motor can cause the switches to open. Replace it if that’s the case with your heater.

5 Flashes: The flame sensor detects flame but the gas valve isn’t energized. Low gas pressure can cause this issue. So, have it checked and fixed.

Steadily On: This one is a huge problem as it indicates control board failure. You should call in a technician if this happens.


Why is there Mr Heater Big Maxx No LED light?

If the power is on and the LED light doesn’t turn on, the problem may be with the control board of the heater. The light may also be turned off because of a safety lockout. 

What to do if Mr Heater Big Maxx keeps shutting off?

The most common issue with the Mr Heater Big Maxx is that the vacuum hose keeps getting clogged. That stops the pressure switch from working properly.

Aim to clean the vacuum hose at least once every six months. This will save you a lot of money in the long run by not having to call in a technician.

What causes Mr Heater Big Maxx no green light?

If the green light isn’t on, it means the power is not on. This can be due to a faulty power outlet, tripped circuit breakers, or a bad transformer.

What does it mean if Mr Heater ignites but shuts off after a while?

The problem is most likely a faulty flame sensor if the heater ignites but shuts off automatically. Cleaning the heater will solve the problem.


We’ve discussed the most common Mr Heater Big Maxx problems in this guide. Follow the fixes we shared to make your heater function properly.

If the problems are too technical, call a technician and don’t take any unnecessary risks. Drop a comment below if you have any questions about fixing Mr Heater Big Maxx heaters.

About David

David is a man who loves doing research and finding out the best solution to any type of heating appliance issues like heaters and fireplaces. Whenever he finds the perfect solutions to any issues of heating appliances after doing in-depth research, he loves to share them with his readers. In fact, his aim is to help his readers to fix the issues with their heating appliances easily.More about us .

6 thoughts on “Mr Heater Big Maxx Problems [How To Fix]”

  1. Hi, I’ve had my big Max heater for a week now and it started out with a code for and then it progressed into not working at all and I don’t know what is wrong with it I’m gonna pursue the warranty that maybe they will just give me another one and I’m not sure if I want another one because I am very disappointed in this one so wish me good luck and maybe I’ll post something to the effect that they corrected the problem end of message.

    • Hi Art

      As you have warranty coverage, it’s better to take help from Mr heater’s customer support center to fix your heater.

      Wish you a fresh & problem-free heater.

  2. We went thru several days of brutal wind chills. Mine doesn’t want to shut off. Room temp is where it’s supposed to be but heater keeps running but not getting warmer that what room temp is sat for. Shuts off for less than 5 mins & it starts back up again. Any advise on this?

    • Hi Lori

      To fix the issue, clean the heater thoroughly.

      If cleaning doesn’t bring luck, contact the manufacturer’s customer support center.

      Best of luck!

  3. Hi there. Have the 3 flashes error code. Cleaned out the metal piece attached to the vacuum hose with a drill bit. Blew into it to get the pressure switch to flip. Replaced the pressure switch and still have the same 3 flashing light code. Thinking of replacing the circuit board next. Any recommendations?

    • Hi Derrick

      To fix the issue, it would be wise to contact the Mr Heater customer support center or hire a certified technician to inspect your heater to find out the main culprit behind the issue & fix it.

      Best of luck!


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