Midea Air Conditioner Error Code E4

The E4 code means the main control board did not receive any communication feedback from the display board within 120 seconds. This communication timeout causes the unit to stop normal operation and display the fault code. The error points to a problem in the signal wiring between the two boards or a failure of one of the boards itself.

A power reset may temporarily clear the error, but if the underlying communication fault is still present, the E4 code will return within 120 seconds of the unit restarting. A reset is useful for confirming whether the fault is intermittent or persistent, but it does not fix the root cause. The signal wiring and boards should be inspected before assuming a reset has resolved the problem.

If the fix is simply reseating a loose connector, there is no parts cost and only minimal labor time involved. If the signal wire harness needs replacement, parts and labor costs are typically in the range of $50 to $150. Replacing a display board or main control board generally costs between $100 and $350 depending on the specific model and labor rates in your area.

In many cases, yes. Start by powering off the unit and inspecting the signal wire harness between the display board and main control board for loose, disconnected, or visibly damaged connectors. Reseating the connectors and restarting the unit resolves the issue when a simple connection problem is the cause. If the wiring checks out and the error returns, board replacement is likely needed and may require a technician.

The unit will generally not operate normally while the E4 fault is active, as the communication failure prevents reliable control of the system. Attempting to bypass or ignore the fault is not recommended. Address the underlying wiring or board issue before returning the unit to service to avoid further component damage.