Mitsubishi Electric Ecodan Heat Pump Error Codes

Complete diagnostic guide for Mitsubishi Electric Ecodan heat pumps in the United Kingdom.

Flow and Water Problems

Error codes for Mitsubishi Electric Ecodan heat pumps related to flow, water circulation and pressure problems.

Error CodeMeaningPossible CausesSolutions
L9Low flow in primary circuit
  • Water circulation problems
  • Air in system
  • Zone valves not activated
  • Pumps not activated
  • Blocked flow
  • Insufficient water flow
  • Check water circulation in primary circuit
  • Bleed system completely
  • Activate zone valves
  • Check pumps for function
  • Increase flow
  • Check system for blockages
  • Contact qualified service if problem persists

Pressure and Refrigerant Circuit Problems

Error codes for Mitsubishi Electric Ecodan heat pumps related to pressure and refrigerant circuit problems.

Error CodeMeaningPossible CausesSolutions
U1High pressure error
  • Abnormal water flow in primary circuit
  • High pressure in refrigerant circuit
  • Blocked heat exchanger
  • Problems with refrigerant circuit
  • Check water flow in primary circuit
  • Monitor pressure in refrigerant circuit
  • Check heat exchanger for blockages
  • Check refrigerant circuit
  • Contact qualified service if necessary
F3Low pressure switch error
  • Low pressure switch defective
  • Low pressure in refrigerant circuit
  • Refrigerant shortage
  • Problems with refrigerant circuit
  • Check low pressure switch for function
  • Check pressure in refrigerant circuit
  • Check refrigerant amount (only by qualified service)
  • Have refrigerant circuit checked for leaks
  • Contact qualified service if necessary
F5High pressure switch error
  • High pressure switch defective
  • High pressure in refrigerant circuit
  • Blocked heat exchanger
  • Problems with refrigerant circuit
  • Check high pressure switch for function
  • Monitor pressure in refrigerant circuit
  • Check heat exchanger for blockages
  • Check refrigerant circuit
  • Contact qualified service if necessary

Sensor and Temperature Errors

Error codes for Mitsubishi Electric Ecodan heat pumps related to sensor and temperature problems.

Error CodeMeaningPossible CausesSolutions
P1Room temperature sensor error (TH1)
  • Room temperature sensor (TH1) not connected
  • Sensor short-circuited
  • Cable connection interrupted
  • Sensor defective
  • Check room temperature sensor (TH1) for proper connection
  • Check sensor for short circuit
  • Check cable connection
  • Test sensor with multimeter
  • Replace sensor if defective
  • Contact qualified service
P6Overheating at heat exchanger
  • Insufficient water flow
  • Air in system
  • Incorrect flow
  • Blockage in heat exchanger
  • Pump problem
  • Increase water flow
  • Bleed system completely
  • Check and correct flow
  • Check heat exchanger for blockages
  • Check pump for function
  • Allow system to cool down
  • Contact qualified service if problem persists

Fan and Motor Errors

Error codes for Mitsubishi Electric Ecodan heat pumps related to fan and motor problems.

Error CodeMeaningPossible CausesSolutions
U8Fan motor error
  • Blockage around fan
  • Fan motor defective
  • Circuit board defective
  • Wiring damaged
  • Problems with fan control
  • Check fan for blockages and remove
  • Test fan motor for function
  • Check circuit board for errors
  • Check wiring
  • Have motor or circuit board replaced if defective
  • Contact qualified service

Electrical and Voltage Errors

Error codes for Mitsubishi Electric Ecodan heat pumps related to voltage and electrical problems.

Error CodeMeaningPossible CausesSolutions
U9Overvoltage or undervoltage
  • Overvoltage in power supply
  • Undervoltage in power supply
  • Problems with power supply
  • Electrical connection problems
  • Check power supply
  • Check voltage in power supply
  • Check electrical connections
  • Contact electrician if necessary
  • Check stabilizer or voltage protection

Need More Help?

If you are experiencing problems with your Mitsubishi Electric Ecodan heat pump that are not covered by these error codes, or if the provided solutions do not resolve your issue, we recommend:

  • Consult your Mitsubishi Electric Ecodan heat pump user manual for model-specific information
  • Visit the official Mitsubishi Electric support page for Ecodan owners: les.mitsubishielectric.co.uk/homeowners/heat-pump-faqs
  • Contact Mitsubishi Electric customer service in the United Kingdom for technical support
  • Seek help from a qualified heat pump repair technician
  • Check warranty coverage if your heat pump is still under warranty
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