Mr Heater Big Maxx 2 Flashes [5 Easy Solutions]

The number one reason behind Mr Heater Big Maxx 2 flashes is a dirty flame sensor. You can easily get rid of this issue by cleaning it.

mr heater big maxx 2 flashes

Besides that, the other reasons that can also cause this problem are:

  • Malfunctioning Igniter.
  • Low Gas Pressure.
  • Bad Gas Valve.
  • Excessive Gas Supply.

Keep on reading this guide to find out more about these problems and find out how you can solve them. Without further ado, let’s dive in!

Mr. Heater Big Maxx 2 Flashes [5 Easy Solutions]

The LED flashing twice on your Mr Heater Big Maxx indicates system lockout failure. It means the system is unable to detect or sustain the flame.

mr heater big maxx indicates system lockout failure

We’ll explore the major reasons behind this problem and its solution in this section.

1. Dirty Flame Sensor

A dirty flame sensor is the most common reason behind seeing Mr Heater Big Maxx LED 2 flashes on the control board. During normal operation, the flame sensor senses the heat, the heat exchanger gets hot, and the fan kicks in.

mr heater dirty flame sensor

Unfortunately, the flame sensor can get clogged and dirty with time. When that happens, it won’t be able to detect the heat from the burners. The end result is seeing the Big Maxx heater 2 flashes code.


Cleaning the flame sensor will do the trick in most cases. Get 120 grit sandpaper and rub it against the flame sensor to remove all the dirt and debris in it. It’s rare but the flame sensors can also break at times. In such cases, you’ll have to replace the flame sensor.

2. Malfunctioning Igniter

The automatic spark ignition system is responsible for igniting the heater. If the igniter works correctly, the heater will automatically light up. There’s no need to light it up manually.

mr heater malfunctioning igniter

But if the igniter goes bad, the flame won’t light up properly. If the unit doesn’t light up at all and you see the Mr Heater Big Maxx 2 flash code, it’s a strong indicator of a bad igniter.


If you have a faulty igniter, you’ll have to replace it. You can call the customer support team of Mr Heater to get assistance on how to go about replacing it. They’ll replace it for you if you’re covered under warranty.

3. Low Gas Pressure

The size of gas pipes need to be of the correct size to provide the right gas pressure to run the heater. For natural gas, a line pressure of 7” WC must be maintained when you size the piping.

mr heater low gas pressure

For propane gas (LPG), the correct line pressure is 13” WC. Not maintaining these things can cause the heater to go out. When installing the heater, your gas utility company most probably installed a regulator between the gas tank and the heater.

It can be used to measure the gas pressure and find out if there’s an issue with it. Before doing any diagnosis, make sure the gas supply is turned on first. It should be parallel to the pipe.

If there’s any smell of gas, stop diagnosing and exit your room. It’s a sign of a leak in the gas pipes. Call your local gas company and follow their instructions.


The help of someone from your local gas utility company is required to solve this issue. He’ll have to come and check the gas pressure and fix it if there’s any fault in it.

4. Bad Gas Valve

There’s a manual gas valve that must be turned on for the heater to work properly. It can be controlled by a rotatory switch knob. If this valve goes bad, there’ll be issues with the gas supply and it can trigger the error code.

mr heater bad gas valve


The Mr Heater Big Maxx bad gas valve must be replaced or repaired when it goes bad. Only then, the heater will have a proper flow of gas. That’s how it can get out of the system lockout failure to detect or sustain flame mode.

5. Excessive Gas Supply

Too much gas supply is just as bad as a low gas supply. Seeing your Mr Heater Big Maxx short cycling is a strong indicator of that. The flame will be shutting off and kick back on its own when it happens.

You’ll know if there’s an excessive gas supply to your heater if you see a flame that’s too blue. It’ll trigger the high-limit sensor of the heat exchanger. When it gets too hot, the flame gets shut off. That’s what causes the short cycling.


Reduce the amount of gas supplied to the heater by turning the gas valve. Crank down the gas supply only a little bit should take care of the problem. If the issue still persists, call a technician to help you out.


What do Mr Heater Big Maxx flash codes mean?

Different codes have different meanings. Check out the back of your side cover of the heater or your owner’s manual to find out what each flash codes mean.

What does Mr Heater no green light mean?

If you don’t see a green light on the control board of Mr Heater, it means that there’s no power to the unit. The common culprits behind it are bad power outlets or tripped breakers.

What to do if you’re facing Mr Heater Big Maxx pressure switch problems?

A stuck pressure switch is one of the most common issues in Big Maxx heaters. You can solve it by cleaning the vacuum hose that’s connected to the switch as well as the nipple of the hose.

Is it normal for the green light in Mr Heater Big Maxx to not flash?

A steady green light is not a good sign in Bigg Maxx heaters. Usually, it indicates control board failure. You shouldn’t take this issue lightly and get in touch with the support team immediately to solve this problem.


What causes Mr. Heater Big Maxx 2 flash? By now, you should have a clear answer to that question. Hopefully, this guide will help you figure out why you’re seeing a couple of flashes on your Big Maxx heater and solve the issue.

You can read our troubleshooting guide on all the common heater issues faced by Mr. Heater users.

Let us know what was causing the issue by leaving a comment below. Feel free to ask any questions about Mr. Heater’s Big Maxx units.

About William

William is the founder of He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

2 thoughts on “Mr Heater Big Maxx 2 Flashes [5 Easy Solutions]”

  1. How do you remove the electrode igniter and electrode sensor when the screws that hold them in are put in from the back side.
    Model # HSU 45 / HSU 75 Purchase 04/2007 serial# MHS-0290685


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