Thermostat displays E2 and shows incorrect or no room temperature reading

Safety first: Switch off power to the furnace/air handler at the breaker before removing the thermostat.

Steps to troubleshoot:

• 1. Check environment: Ensure the thermostat is not installed where it can be exposed to steam, direct moisture, or dripping water (e.g., near showers or humidifiers). Dry any visible moisture with a soft cloth.
• 2. Power cycle: Turn off the HVAC breaker for 2–3 minutes, then restore power. Observe if E2 clears.
• 3. Remove thermostat from wall plate: Gently pull the Emerson thermostat straight off the sub-base. Inspect the back of the thermostat for corrosion, moisture, or debris around the vent slots where the sensor resides.
• 4. Clean carefully: If light dust or debris is present, use a can of dry compressed air to blow out the vents. Do not use liquids or aggressive cleaners.
• 5. Factory reset: Perform a factory reset from the settings menu. Reconfigure Wi‑Fi and system type, then check if E2 returns.
• 6. Persistent E2: A shorted sensor or PCB trace usually requires replacing the thermostat; internal sensor components are not serviceable.

When to call a professional: If the thermostat is in a high-humidity environment or shows corrosion, consult an HVAC technician to relocate and replace the thermostat.