Samsung Air Conditioner Error Code E191

E191 indicates a pipe test error involving the EVA_OUT (evaporator outlet) temperature sensor on one or more indoor units. The system either detected no temperature change at the expected indoor unit's EVA_OUT during a pipe test, or detected a change at the wrong unit. This points to an address mismatch between the indoor unit and the MCU, or a sensor-related fault.

The E191 error is not a safety-critical fault in the sense of an electrical hazard, but it does indicate the system cannot properly verify refrigerant distribution across indoor units. Operating the system long-term with this fault unresolved could result in uneven cooling, potential compressor stress, or other performance issues. It is best to have the error diagnosed and corrected promptly.

If the fix is a simple address switch reconfiguration, labor costs from a technician visit may range from around $75 to $200 depending on your location and service provider. If the EVA_OUT temperature sensor needs replacement, parts can add an additional $20 to $80 or more. If a PCB replacement is required, total repair costs could range from $200 to $600 or higher. Getting a diagnostic quote from a Samsung-authorized technician is recommended.

Start by checking that the address switch on each indoor unit's PCB matches the address assigned on the MCU. If there is a mismatch, correct the switch setting and re-run the pipe test. Also inspect the EVA_OUT temperature sensor and its wiring for damage or disconnection. If the error persists after addressing corrections, a qualified technician should inspect the communication wiring and MCU configuration.

A simple power reset is unlikely to permanently clear E191 because the underlying cause is a configuration or hardware issue rather than a temporary communication glitch. The error will typically return when the system runs its pipe test again. The root cause, usually an address mismatch or sensor fault, must be corrected before the code will clear reliably.