TradeAssistIQHome

Mitsubishi Ecodan fault E8

Applicable error for automatic backup heat source operation

Heat pump

What it means

One of the error codes listed as applicable for automatic switch to backup heat source operation when the outdoor unit stops abnormally.

Likely causes

  1. Hot water run out
  2. Prohibit, schedule timer or holiday mode selected
  3. Heat pump not working
  4. Booster heater cut-out tripped
  5. Earth leakage circuit breaker for booster heater breaker (ECB1) tripped
  6. Booster heater thermal cut-out tripped and cannot be reset using manual reset button
  7. Immersion heater cut-out tripped
  8. Immersion heater breaker (ECB2) tripped
  9. 3-way valve fault
  10. Outdoor unit abnormal stop triggers automatic backup operation

Where to start

  1. Ensure DHW mode is operating and wait for DHW tank to re-heat
  2. Check settings and change as appropriate for prohibit/schedule/holiday mode
  3. Check heat pump - consult outdoor unit service manual

The full answer, free

  • 15 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 17), right under the answer
Ask about E8 freeCreate a free account

Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.

From the Mitsubishi manual for the Ecodan. Check the model on the data plate before you order parts.

Other Mitsubishi Ecodan fault codes