Automation . Firmware Updates . Hardware Engineering . Smart Home
Ecobee Smart Thermostat Firmware 4.9.227 Triggers HVAC_FAULT_E5 on Heat Pumps
Dated: March 2, 2026 — Ecobee firmware 4.9.227 A recent Ecobee firmware update is reportedly throwing a reversing valve fault on heat pump systems running auxiliary electric strip heat, especially during defrost cycles where the reversing valve toggles through the O/B terminal. Owners describe the fault locking out the compressor briefly and dropping the system […]







