Ignition Lockout Due To Retries [9 Easy Fixes]

Your furnace goes into ignition lockout due to retries when the flame sensor repeatedly fails to detect the igniter’s spark and doesn’t release gas for ignition.

Depending on your heater model, different error signals pop up to indicate ignition lockout meaning. Commonly, you get 3 consecutive LED flashes, or an error message is displayed saying, “IGNITION LOCKOUT” or “ERR IGN”. 

What causes ignition lockout? Several reasons can cause ignition lockout faults. The possible causes include insufficient gas pressure, dirty air filter, clogged exhaust, and defective flame sensor.

Plus, a faulty circuit board, insufficient voltage supply, clogged burner orifice or head, defective heat exchanger, and malfunctioning thermostat could be the culprit behind the lockout problem.

Keep reading our ignition lockout troubleshooting guide to fix your heater.

Table Of Contents

Ignition Lockout Due To Retries [9 Easy Fixes]

Now, we will take a deeper look at the causes of lockout due to failed ignition on the furnace as well as the simplest solution for each one.

Note: You can also read how to fix the Atwood furnace ignition lockout fault.

1. Insufficient Gas Pressure

For most models of furnace, the pressure reading on a U-Tube water manometer has to be 11″ W.C. or 27 mbar with the heater and other gas appliances switched on.

When your heater is running on low gas pressure, it results in ignition lockout, sooting from premature combustion as well as heating chamber failure. 


A manometer must be attached to the gas valve. You will find a 1/8″ MPT plug on the valve’s outlet section. Remove the plug. Put a 1/8″ brass barb into the vacant space left by the removal of the MPT plug.

To ensure that the barb tap is tight and that no gas leaks from the corners, falsifying the measurement, a threading sealant is advised.

Once the digital manometer is connected to the gas valve, the burner can be turned on. Rotating the pressure regulator adjustment screw changes the gas pressure.

The clockwise rotational movement will increase pressure while anti-clockwise rotation decreases it.

2. Dirty Air Filter

Your heater’s filter may be clogged with dirt causing a lack of proper ventilation. In this situation, your furnace will overheat and trip safety switches.

After that when you try to relight the furnace, an ignition lockout may occur. 


The solution to this problem is straightforward. You need to clean up the air filter. Some air filters can’t be reused. In that case, replace the air filter.

However, to clean up a reusable air filter, you can simply rinse it out with a garden hose after removing it from the heater. Once clean, dry it before reinstalling it. 

3. Clogged Exhaust

To let the combusted air and excess heat out of your furnace, you need a working exhaust. All that heat is held inside if dirt and debris block the heater exhaust.

As a result, the heater overheats and shuts down for safety reasons. Your burner will be shut off as well, resulting in a loss of ignition.


The following instructions will show you how to clean your heating vent.

  • Locate your furnace’s vent pipe. Put on rubber gloves, safety glasses, and any other dust protection before removing the vent cap with the screwdriver.
  • Once the vent is opened, you can see inside. To reach any dirt that has become lodged, use a metal wire or plastic hook.
  • Use the handheld vacuum to clean out any remaining dirt. After wiping the cap clean with a rag or soft cloth, replace it.
  • Remove any hard objects that may be obstructing the pipe and allowing debris to accumulate inside. If necessary, relocate the heater.

4. Defective Flame Sensor

The ignitor’s flame will not be detected by a failing furnace flame sensor, and the burner gas valves will not release gas in time for ignition. An ignition lockout occurs as a result of this.


You should first check the flame sensor with a multimeter to determine if it is working. A reading of 5-10 µA means that the flame sensor is working properly. Otherwise, the flame sensor should be replaced.

5. Faulty Circuit Board

A heater with a faulty circuit board can cause a variety of issues and error messages, including ignition lockout. If this is the case with your heater, the expense of repairing it will be considerable.


Examine your control panel. The presence of burn marks or a foul odor indicates that the control board has been damaged. Check to see if electricity is flowing into and out of the control board as it should.

You must replace the board if it is found to be defective. Hire a certified electrician to help you replace the control board.

Alternatively, watching the video will be helpful if you want to do the task by yourself.

6. Insufficient Voltage Supply

It’s possible that your heater isn’t getting enough power. To power your furnace, you’ll need a 120 or 240-volt supply.


Make sure the power outlet where your heater is plugged in is labeled with the required voltage. You need to connect the heater to another plug if the outlet voltage is lower.

Check the power received by your heater with a multimeter. If it’s not up to par, contact your local power company to find out what’s wrong.

7. Clogged Burner Orifice or Head

A clogged burner head or orifice is another common cause of an ignition lockout on a furnace. Dirt, debris, and grease can build up in your burner head over time due to use. The dirt acts as a barrier to ignition. As a result, ignition failure occurs. 


The burner assembly of your furnace needs to be cleaned. Here’s how you do that. 

  • Your heater’s electricity and gas supply must be turned off. Remove the burner assembly. After that, the actual cleaning begins.
  • With a small brass wire brush, poke the end of each burner facing the furnace combustion chamber.
  • Blow compressed air into the burner through the opposite end of the brush to remove combustion leftovers, then brush until all deposits are gone.
  • Ensure that debris is blown out of both sides of the burner’s fins. The flames pass through these fins, lighting up each burner. If you don’t have an air compressor, you can use a can of pressurized gas.
  • Reassemble your heater after replacing the burner assembly.

8. Defective Heat Exchanger

Furnace ignition lockout can be caused by a faulty heat exchanger. In most cases, a heat exchanger has two different elements. Your heater will not be able to heat without this component.


To replace a heat exchanger, follow the steps below.

  • Remove the heat exchanger’s access panel with a screwdriver. Take a picture of the connections once you have access to the heat exchanger.  
  • With the screwdriver and wrench, remove the heat exchanger from its mounting. Once they’ve been removed, you should be able to easily pull out the heat exchanger.
  • Set it aside while you work on the replacement heat exchanger. As needed, begin reinstalling and tightening the fittings.
  • With the new heat exchanger in place, replace the panels and turn the power back on. The system will need time to prime itself before it can operate.

9. Malfunctioning Thermostat

When the thermostat in your heater malfunctions, it might block ignition and result in an ignition lockout.


First, use a multimeter to check your thermostat. A reading of “0” Ohms or as close to zero as practicable should be obtained.

If not, your thermostat is broken and must be replaced. We recommend that you have your thermostat replaced by a licensed electrician.

Well, check all the issues one after another & try to find out the main culprit behind the issue. Just follow our above-mentioned guidelines to fix the underlying problem & finally, you’ll get your furnace working.


How do you know if your furnace ignitor is bad?

The failure to ignite is the clearest evidence that your ignitor is defective. You can get a view of your igniter when turning on the heater. If it produces a spark, it is running fine. Otherwise, it is malfunctioning.

How much does it cost to replace an igniter on a furnace?

Replacement of a heater ignitor–including parts and labor–costs roughly $300 – $425 for a trained contractor to install, depending on whether you have natural gas, oil, or propane furnace. Consider the expense of replacing a draft inducer motor, which might range from $400 to $1,500.

Can I clean a furnace ignitor?

Yes, you can clean the furnace ignitor. Using a can of compressed air will be enough. However, you can rub the igniter with an emery cloth or steel wool to remove more stubborn grime.

Why is my furnace not running?

Filters that are clogged are the most prevalent source of furnace issues. Dust and filth hinder airflow, the heat exchanger gets overheated and the safety system shuts down the heater.

How many times can I hit the reset button on my furnace?

Don’t press the “reset” button more than twice. Without ignition, resetting the heater spills oil into the burner chamber, where it gets stored. The furnace can then start explosively when it eventually does. 


Now that you know all you need to know about ignition lockout due to retries, hopefully, you can fix your heater ASAP.

In case you need more troubleshooting tips for your heater, leave us a comment below.

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