Dewalt Diesel Heater Problems [5 Easy Solutions]

Some common Dewalt diesel heater problems are the heater not igniting or won’t stay lit. In addition, the heater not sparking, blowing smoke, and spitting fuel are also frequent issues.

dewalt diesel heater problems

However, read our today’s comprehensive guide on Dewalt diesel heater troubleshooting. It’ll certainly help you sort out your heater problem in no time and fix it by yourself. So, let’s begin…

Dewalt Diesel Heater Problems [5 Easy Solutions]

Read the below section to find out the reasons behind your heater troubles and their solutions: 

Note: You can also read the Dewalt propane heater troubleshooting guide.

1. Dewalt Diesel Heater Not Igniting

The main reason behind your Dewalt diesel heater not igniting is the clogged air and fuel filter due to dirt. When both filters get clogged, it causes an imbalance between the fuel and air mixture which prevents your heater from igniting. 

Plus, insufficient fuel and power supply from the battery can also be the reasons for your diesel heater not igniting. 


  • First, make sure the heater fuel tank has enough fuel to start. 
  • Then ensure enough airflow and a balanced mixture of fuel and air. To make it happen, remove the exhaust pipe or pilot tube and air inlet pipe from your heater. Wash and clean them. But, when you notice that they have become black with full of carbon, then replace the air inlet pipe and exhaust pipe. Also, clean the fuel and air filter. 
  • Check and find the battery is full of charge. Also, ensure the battery connection is correctly connected to the heater’s original wiring set. 

2. Dewalt Heater Keeps Shutting Off

When your Dewalt diesel heater pilot light gets dirty and blocked or faulty, your heater will go out frequently. Plus, somehow you might activate the tip-over switch which is letting your heater shut off. Besides, the following reasons could be the culprits to turn off your heater often:

  • Dead or low-charged battery
  • The battery isn’t directly connected to the battery wiring loom
  • Dirty fuel filter   
  • Dirty air intake and output
  • Insufficient pump and air pressure
  • Incorrectly installed photocell assembly
  • Defective wiring
  • Empty fuel tank or low-quality fuel
  • Defective control board


When you find your Dewalt diesel heater keeps turning off frequently, go for the following fixes:

  • Clean the pilot light and remove any blockage. If the pilot light is defective, replace it.
  • Make sure the tip-over switch is off.
  • Ensure the heater battery is fully charged. In case of a dead battery, you need to change it.
  • Clean the fuel filter, air intake, and output hole and make sure there is no obstacle. 
  • Adjust the pump and air pressure.
  • Check and ensure the photocell assembly is installed correctly.
  • Find out if there is any faulty or damaged electrical connection between the main PCB and photocell and fix them. 
  • Check the fuel tank and ensure it has enough quality fuel. Don’t use contaminated or bad fuel. 
  • Finally, check if there is any defect in the control board of your heater. If it’s defective, replace it by getting help from Dewalt customer service. 

3. Dewalt Diesel Heater Blowing Smoke

When your diesel heater combustion chamber, heat exchanger, and air filter get dirty and clogged, it leads to incomplete combustion of the fuel. As a result, your heater begins to blow smoke. Besides, if the air and fuel mixture is in the off position, your heater will give off sooty smoke.

Most importantly, if the dirt accumulates from fuel and carbon blocks the nozzle passages, the air, and fuel flow gets reduced. And it will result in imbalanced air and fuel mixture. As a result, your heater will emit a bad odor and smoke. 


  • Clean nozzle passages and nozzle. If it doesn’t work, replace the nozzle. 
  • Clean the air filter, heat exchanger, and combustion chamber of your Dewalt diesel heater. 
  • Adjust the air and fuel setting. 

Pro Tips: You can use a diesel fuel additive. It will improve the burning performance and rid your heater of smoke. And always run your heater on high before you go to shut it off. It will burn off the soot and reduce the blowing of smoke.  

4. Dewalt Diesel Heater Spitting Fuel

Your Dewalt heater may start spitting fuel out of it when its fuel hose going from the fuel tank to the burner gets damaged or clogged. Also, faulty or clogged air hoses can be the reason behind fuel splitting. 

defective fuel hose of dewalt diesel heater


  • Check the fuel hose. And if it’s defective, replace it with a new one. Plus, don’t forget to clean the fuel filter also.
  • Also, check the air hose and clean it or replace the air hose if it’s faulty.

You can also watch the tutorial below to fix the fuel-splitting issue.

5. Dewalt Diesel Heater No Spark

The following are the common reasons behind our Dewalt diesel heater not sparking:

  • If the extension cord is too lengthy and fails to draw proper AMP. 
  • Disconnection or damaged wires to the igniter.
  • More gaps between  electrode probes
  • Dirty or faulty igniter assembly.
  • Defective oil flame control assembly


  • Check the extension cord and make sure it’s drawing proper AMP.
  • Check the wiring to the igniter and make sure there is no disconnection or damage.
  • Keep a gap of  (2.3 – 3mm) between  electrode probes
  • Clean the igniter. If it’s faulty, replace it.
  • And finally, replace the oil flame control assembly if it’s defective.


What is the smell coming out of my diesel heater?

When the air and fuel filter becomes dirty, it causes an imbalance in the fuel and air mixture. This imbalance of air and fuel mixture creates bed smells. Plus burnt dust and insects inside heater creates a bed smell. Cleaning heater air and fuel filter and your heater can stop bed smells coming from your heater.

Final Verdict

Hopefully, we could help you out by finding the issues with your Dewalt diesel heater and providing you with the solution as well. To deal with the Dewalt diesel heater problems, just follow our guide. This will certainly help you sort out the issue first and then fix it in no time to restore its best condition. 

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.

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