Midea M2OC-18HFN1-M Service Manual page 58

9.4.2.2 E2(Communication malfunction between indoor and outdoor units) error diagnosis and solution.
Error Code
Malfunction decision
conditions
Supposed causes
Trouble shooting:
E2
Indoor unit does not receive the feedback from outdoor unit
during 120 seconds or outdoor unit does not receive the
feedback from any one indoor unit during 180 seconds.
● Wiring mistake
● Indoor or outdoor PCB faulty