Troubleshooting Codes

 

Diesel Heater Error Code Index

 

Error Code: E-01 — Undervoltage

What this means:
The heater is not receiving enough electrical power to operate. This most commonly occurs when the battery voltage drops too low, especially during startup when the heater draws the most power.

Common Causes

  • Battery is low or not fully charged
  • Voltage drop during startup due to high power demand
  • Heater is set to the incorrect voltage
  • Loose, damaged, or undersized power connections
  • Long power cable runs causing voltage loss

Troubleshooting Steps

  1. Recharge the Power Source
    Fully charge the battery or power supply before turning the heater back on.
    Tip: A weak battery may show 12V when idle but still fail during heater startup.
  2. Confirm Correct Voltage Setting
    Verify the heater is set to the correct system voltage (12V). An incorrect voltage setting can immediately trigger this error.
  3. Inspect the Main Power Connection
    Ensure the main wiring harness connector is fully seated, secure, and free of corrosion or damage.
  4. Check Battery Voltage During Startup
    The heater draws the most current during startup. Voltage should remain above approximately 11.5V. If voltage drops below this level, the heater will shut down with an E-01 error.
    Tip: Starting the heater while the vehicle engine is running can help prevent this issue.
  5. Inspect Power and Ground Wiring
    • Use short, thick power cables (10–12 AWG recommended)
    • Avoid cigarette lighter plugs or thin extension wiring
    • Ensure the ground wire is connected to clean metal or directly to the battery negative terminal
  6. Using a Portable Power Station
    Some small power stations cannot supply enough current during startup.
    • Confirm the unit supports at least 15–20A surge current
    • If E-01 appears immediately on startup, the power station may be undersized

If the Error Persists

The battery may be worn out or the wiring may not be capable of supplying sufficient current. Replacing the battery or upgrading the wiring typically resolves this issue.

Error Code: E-02 — Overvoltage

What this means:
The heater is receiving voltage higher than its safe operating range. To protect internal electronics, the system shuts down.

Common Causes

  • Battery charger or alternator output is too high
  • Incorrect voltage setting on the heater
  • Unregulated power supply
  • Poor wiring causing unstable voltage spikes

Troubleshooting Steps

  1. Check Power Source Voltage
    Confirm the supply voltage does not exceed safe 12V operating limits.
  2. Verify Heater Voltage Setting
    Ensure the heater is set to 12 volts.
  3. Inspect Main Harness Connection
    Make sure the wiring harness is fully seated and secure.
  4. Test With Engine Off
    If installed in a vehicle, test the heater with the engine off to rule out alternator overcharging.

If the Error Persists

Continued overvoltage can damage internal electronics. A voltage regulator or inspection of the charging system may be required.

Error Code: E-03 — Ignition / Glow Plug Failure

What this means:
The heater was unable to ignite fuel. This is commonly related to the glow plug or insufficient electrical power.

Common Causes

  • Failed or damaged glow plug
  • Loose or corroded glow plug wiring
  • Low battery voltage during startup

Troubleshooting Steps

  1. Inspect the Glow Plug
    Check for carbon buildup, damage, or loose connections.
  2. Check Wiring Connections
    Ensure glow plug wiring is secure and undamaged.
  3. Verify Battery Voltage
    Low voltage can prevent the glow plug from reaching ignition temperature.

If the Error Persists

The glow plug may need to be replaced.

Error Code: E-04 — Fuel Pump Failure

What this means:
The heater cannot deliver fuel because the fuel pump is not operating correctly.

Common Causes

  • Fuel pump not receiving power
  • Damaged or disconnected fuel pump wiring
  • Blocked or kinked fuel lines
  • Low battery voltage

E-05 Error Code – Overheating

Important Overview:
In 95% of E-05 cases, the cause is too many bends or restrictions in the heat tube. This creates back-pressure, which forces hot air back into the heater and triggers overheating. The good news: this is very easy to diagnose and fix.

What Causes E-05?

If the internal temperature of the heater exceeds 260°C, the temperature sensor automatically initiates a shutdown to protect the unit. The most common reason for this is restricted airflow in the heat tube, but a few other issues can also cause it.

Step-By-Step Troubleshooting

Step 1 — Remove the Heat Tube (Most Common Fix)

  1. Let the heater finish its shutdown cycle and disconnect it from power.
  2. Allow it to cool completely.
  3. Remove the heat tube from the heater.
  4. Restart the heater with no heat tube attached.

If the heater runs normally with the tube removed, the heat tube setup is the problem.

Fix the heat-tube setup by checking:

  • There should be as few bends as possible.
  • The longer the heat tube, the more important it is that it remains straight.
  • Ensure no kinks, crushed areas, or restrictions are present.

If Step 1 does NOT solve the issue, continue with the steps below.

Step 2 — Check Power Source

  • Ensure your battery/power supply has sufficient voltage and is not sagging under load.
  • Reconnect power and perform a quick reset cycle.

Step 3 — Inspect Intake & Exhaust

  • Verify that the air intake and exhaust pipes have no blockages or debris.
  • The exhaust pipe should have only one bend, located right at the heater outlet, and that bend should be no less than 90°.
  • Ensure the heater is operated in a well-ventilated environment.

Step 4 — Check the Fan

This may require removing the protective shell of the heater and the top part of the plastic housing.

  • If the fan cannot expel heat properly, the heater will overheat.
  • Low power can slow the fan, so confirm the power source again.
  • Listen for abnormal noises — grinding, buzzing, or slow spinning can indicate worn bearings or a failing motor.
  • Spin the fan manually. It should spin freely with minimal friction.
  • If it sticks or barely moves, the motor or bearings likely require replacement.

Step 5 — Check the Temperature Sensor

  • The temp sensor is located on top of the heat exchanger.
  • Ensure it is positioned correctly and firmly attached.
  • If the heater triggers E-05 before it has time to heat up, the sensor may be faulty or misaligned.
  • The sensor is easy to replace if needed.

Step 6 — Inspect for Carbon Build-Up

If the heat tube, fan, and temperature sensor all check out, the overheating may be caused by internal carbon buildup.

  • Carbon can accumulate in the exhaust port, heat exchanger, and burn chamber.
  • This is more common when running the heater on low settings for long periods.
  • Or when the heater is repeatedly shut off without completing its cooldown cycle.
  • Disassemble the heater and clean components using carb cleaner if needed.

Error Code: E-06 — Motor / Fan Failure

What this means:
The fan motor is not operating correctly or the system cannot detect its speed.

Common Causes

  • Fan motor obstruction
  • Failed motor or hall sensor
  • Incorrect magnet polarity
  • Low battery voltage

Troubleshooting Steps

  1. Check Fan Movement
    Ensure the fan spins freely by hand.
  2. Inspect Sensor and Wiring
    Check hall sensor position and wiring integrity.
  3. Verify Voltage Supply
    Low voltage can prevent proper motor operation.

If the Error Persists

The fan motor or hall sensor may require replacement.

Error Code: E-07 — Controller Communication Failure

What this means:
The heater and controller are no longer communicating.

Common Causes

  • Loose controller cable
  • Damaged wiring harness
  • Low system voltage

Troubleshooting Steps

  1. Check All Connections
    Ensure all plugs are firmly connected.
  2. Inspect Wiring
    Look for pinched, damaged, or broken cables.
  3. Verify Battery Voltage
    Low voltage can interrupt communication.

If the Error Persists

The controller or wiring harness may need replacement.

Error Code: E-08 — Flame Failure

What this means:
The heater was unable to maintain a flame after ignition.

Common Causes

  • Low fuel level
  • Air in fuel lines
  • Blocked fuel filter
  • Low battery voltage

Troubleshooting Steps

  1. Check Fuel Level
    Ensure the tank contains sufficient fuel.
  2. Inspect Fuel System
    Check all fuel lines and connections.
  3. Prime the Fuel Pump
    Prime multiple times to remove air.
  4. Check Voltage
    Low voltage can cause flame loss.

If the Error Persists

The sensor may need replacement.

Error Code: E-10 — Ignition Failure

What this means:
The heater attempted ignition multiple times without success.

Common Causes

  • Fuel delivery issues
  • Blocked fuel lines
  • Unresolved previous errors

Troubleshooting Steps

  1. Inspect Fuel System
    Check fuel pump, lines, and filter.
  2. Verify Fuel Supply
    Ensure fuel reaches the heater.
  3. Clear Other Errors
    Resolve previous faults before restarting.

If the Error Persists

Further diagnosis of the ignition system may be required.

Error Code: E-11 — Ambient Temperature Sensor Failure

What this means:
The ambient temperature sensor is reporting an invalid signal.

Common Causes

  • Damaged sensor
  • Wiring fault

Troubleshooting Steps

  1. Inspect Sensor
    Check for visible damage.
  2. Check Wiring
    Ensure wiring is intact.

If the Error Persists

The ambient temperature sensor may require replacement.

Error Code: E-12 — Controller Overheating

What this means:
The controller temperature exceeded safe operating limits.

Common Causes

  • Blocked airflow
  • Poor ventilation
  • Controller or ECU fault

Troubleshooting Steps

  1. Check Airflow
    Ensure air inlet, outlet, and exhaust are clear.
  2. Inspect Installation
    Confirm adequate ventilation.

If the Error Persists

The controller or ECU may require service or replacement.