Mitsubishi Air Conditioner Error Code Er3

Er3 indicates a calibration error in which the analog input bias and gain calibration values stored in parameters C3, C4, C6, and C7 are set too close together. This prevents the controller from accurately processing analog input signals. It is a configuration issue and not typically caused by a failed hardware component. Correcting the calibration parameter values will resolve the error.

A simple power reset will not permanently clear Er3 because the fault is caused by stored calibration parameter values that remain in memory after a reset. The error will return unless the underlying parameter values in C3, C4, C6, and C7 are corrected. A full factory reset could change the stored values, but this would require reconfiguring all settings from scratch and may not produce the correct calibration values for your installation.

If the error is caused by incorrect calibration parameter settings, the repair cost is primarily the labor charge for a qualified technician to access and correct the parameters, which typically falls in the range of 75 to 200 dollars depending on the technician and region. If a faulty control board is found to be the cause, parts and labor costs can range from 300 to 800 dollars or more. In most cases, Er3 is resolved through parameter adjustment alone without any parts replacement.

Access the unit's parameter settings and check the current values of calibration parameters C3, C4, C6, and C7. Compare these values to the correct calibration specifications for your installation and adjust any bias and gain values that are set too close together. After saving the corrected values, the error should clear. If the error persists after correction, inspect the control board for faults.

Er3 itself is a calibration configuration error and does not directly indicate a dangerous condition. However, because the error means the controller cannot reliably interpret analog input signals, the unit may not operate correctly or may not respond accurately to temperature or pressure readings. It is advisable to address the error before continuing to run the system to avoid potential operational issues.