These error codes and troubleshooting solutions are developed based on LF BROS diesel air heaters.
They are widely applicable to most Chinese diesel parking heaters with similar controller logic.
However, due to differences in brand design, controller versions, and installation conditions, actual behavior may vary slightly between different heaters.
Error Code E0 – Main Control Board Failure
Possible Cause
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The electronic components on the control board are damaged.
Solution
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Replace the main control board.
Error Code E1 – Start-up Failure
Possible Causes & Solutions
Fuel Tank Empty
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Refill with diesel fuel.
Air Bubbles in the Fuel Line
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Check for loose connections in the fuel line and tighten them securely.
Fuel Pump Not Delivering Fuel or Low Output
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Disconnect the fuel hose at the pump outlet and power on the heater.
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Check fuel flow while the pump is running.
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If abnormal, remove the pump and blow air into the inlet with an air gun.
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If the issue remains, replace the fuel pump.
White Smoke
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Check the intake pipe, exhaust pipe, and glow plug air holes for blockage.
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Clear any obstructions.
Fuel Dripping from the Exhaust
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Check that the power supply meets the 150W start-up requirement.
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Inspect wiring for loose connections and check the fuse.
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If extension wiring is used:
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Use 5 mm² cable
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Keep the length under 2 m (6.5 ft)
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Error Code E2 – Flame Off
Possible Causes & Solutions
Air Intake or Exhaust Blockage
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Check that the air intake and exhaust are clear.
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Remove any carbon buildup or debris to ensure proper airflow.
Fuel Line Issue
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Check for air bubbles in the fuel line that may cause intermittent fuel supply.
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Reinstall the fuel line properly.
Error Code E3 – Voltage or Power Supply Error
Possible Causes & Solutions
Incorrect Voltage
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Ensure the heater voltage matches the power supply:
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12V units: 9–18V
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24V units: 18–32V
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If out of range, replace the power supply immediately.
Insufficient Start-up Power
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Heater requires 150W to start.
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If using extension wiring:
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Use 2.5 mm² cable
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Keep length under 2 m (6.5 ft)
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Improper Extension Wiring
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Extension cable must be 2.5 mm² pure fine copper.
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Ensure secure connections.
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Do not use loose or undersized wiring.
Insufficient Current
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Power supply must provide:
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12V: not less than 10A
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24V: not less than 5A
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Poor Connection
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Check that the wiring harness connectors are securely connected to the power supply.
Error Code E4 – Early Ignition
Cause
-
Residual fuel inside the heater after an abnormal shutdown.
Solution
-
Turn the heater off completely.
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Restart the heater.
Error Code E6 – Main Board Sensor Error
Possible Causes & Solutions
Main Board Temperature Sensor Failure
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Power on and check whether the heater ignites.
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If it fails to ignite, the temperature sensor is damaged.
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Replace the main control board.
Main Board Temperature Sensor Over-temperature
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If the heater ignites normally, the air inlet temperature is too high.
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Ensure:
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At least 10 cm (4 in) clearance at the air inlet
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No obstructions around the heater
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Error Code E7 – Fuel Pump Error
Possible Causes & Solutions
Fuel Pump Wiring Open or Short Circuit
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Check wiring for open or short circuits.
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Ensure the fuel pump connector is secure.
Fuel Pump Failure
-
Replace the fuel pump.
Main Control Board Failure
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If wiring and pump are normal, replace the main control board.
Error Code E8 – Motor Error
Possible Causes & Solutions
Motor Overload or Blockage
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Fan blades stuck.
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Check for housing deformation.
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Realign housing if necessary.
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Shipping damage may also cause blade interference.
Fan Magnets Missing or Installed Incorrectly
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Small magnets under the fan may be missing or reversed.
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Reinstall magnets correctly:
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One North pole
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One South pole
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Motor Stall
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Check if the main control board has shifted.
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Reposition if the gap between fan and board is too large.
Wiring Open or Short Circuit
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Motor wiring harness may be loose.
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Reconnect securely.
Motor Failure
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Replace the motor assembly.
Error Code E9 – Glow Plug Failure
Possible Causes & Solutions
Glow Plug Short Circuit
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Check if the positive and negative poles are stuck together.
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Separate if stuck.
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Replace the glow plug if separation does not resolve the issue.
Main Control Board Damage
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If replacing the glow plug does not fix the issue, replace the main board.
Error Code E10 – Main Unit Over-temperature
Possible Causes & Solutions
Air Inlet or Outlet Blockage
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Check and clear any obstructions in air ducts.
Temperature Sensor Fault
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If air ducts are clear but outlet temperature is low, the sensor may be faulty.
Excessive Fuel Output
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High-flow fuel pump incorrectly installed.
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Replace with a properly matched fuel pump.
Error Code E11 – Heating Element Sensor Error
Possible Causes & Solutions
Poor Contact
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Check sensor connector and wiring.
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Reconnect firmly.
Sensor Failure
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Measure sensor resistance.
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Replace sensor if no reading is detected.
Error Code E12 – Glow Plug Open Circuit
Possible Causes & Solutions
Poor Contact
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Check glow plug connector.
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Reconnect firmly.
Main Board Damage
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If issue persists, replace the main board.
Error Code C4 – LCD Controller Error
Solution
-
Check whether the LCD controller is exposed to high temperatures.
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Relocate it away from heat sources.
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If the issue persists, replace the LCD controller.
Error Code C7 / CONN – LCD Controller or Main Board Error
Possible Causes & Solutions
LCD Controller Signal Failure
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Check if the LCD controller connector is loose.
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Reconnect securely.
LCD Controller Electronic Damage
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If reconnection fails:
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Use emergency startup method.
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Wait 10 seconds:
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Fan starts: Replace LCD controller (host wiring is functional).
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No startup: Check wiring harness; replace main board if harness is intact.
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Why LF BROS Error Code Solutions Are Reliable
LF BROS has over 16 years of experience in diesel air heater manufacturing
and long-term after-sales data from multiple overseas markets.
All troubleshooting methods in this guide are derived from real fault cases
and validated through internal testing, making them practical and reliable
for both LF BROS heaters and other similar diesel heaters.
