Mitsubishi Air Conditioner Error Code E.EP

E.EP is an encoder phase fault that occurs during offline auto tuning. The drive detects that the actual rotation direction of the motor, as reported by the encoder, does not match the rotation command it sent. This fault prevents the system from completing its tuning sequence and entering normal operation. It is most often caused by incorrect encoder cable wiring or an improper setting in parameters Pr.359 or Pr.852.

No. The E.EP fault halts the auto tuning process and prevents the drive from operating the motor correctly. Attempting to force operation with this fault active could result in improper motor control and potential damage to the drive or motor. The fault must be diagnosed and resolved before the system is returned to service.

If the fault is caused by a wiring error or incorrect parameter settings, repair costs are typically limited to labor time for diagnosis and correction, often in the range of $75 to $200 depending on the technician and location. If the encoder cable or encoder unit requires replacement, parts costs can add $50 to $300 or more to the total, depending on the specific components involved. Getting a diagnostic assessment from a qualified technician is the best way to estimate the total cost for your specific situation.

Start by inspecting the encoder cable wiring and confirming each signal lead is connected to the correct terminal, paying close attention to the A-phase and B-phase leads. Next, review and correct parameters Pr.359 and Pr.852 to ensure they match the motor and encoder being used. Once wiring and parameters are confirmed correct, clear the fault and retry the auto tuning sequence. If the fault persists after those steps, inspect the encoder cable for damage or test the encoder itself.

A reset will clear the active fault indication, but the fault will return the next time auto tuning is initiated if the underlying cause has not been corrected. Simply resetting without addressing the encoder wiring or parameter settings will not resolve the problem. The root cause must be identified and fixed before the tuning sequence can complete successfully.