Navien water heater displays E027 and stops; often occurs during or after ignition attempts.

Safety: Turn OFF power before opening the unit.

Steps:

• 1. Check venting: Ensure intake and exhaust are clear; heavy restriction can overload the fan.
• 2. Inspect fan area: Remove the front cover and visually inspect the fan housing for debris, insect nests, or foreign objects. Do not stick fingers into the fan blades.
• 3. Check wiring: Locate the fan motor connector on the main PCB and ensure it is fully seated. Inspect the cable for damage.
• 4. Listen for fan speed changes: Restore power and call for hot water. If the fan fails to start, starts slowly, or makes scraping noises, the motor or bearings are likely failing.

Fan replacement requires disassembly of the combustion chamber and should be done by a Navien-trained technician to ensure proper sealing and combustion tuning.