Tankless heater shows E7 and will not ignite; fan may run briefly then stop.

Safety first: Turn OFF power and gas. Working around the combustion fan and venting involves carbon monoxide risk—ensure good ventilation.

• Inspect intake and exhaust: Check both intake and exhaust terminations for obstructions. Clear any debris, nests, or ice. Verify that vent lengths and elbows are within Richmond limits.
• Check fan rotation: Remove the front cover and visually inspect the combustion blower. Spin the fan wheel gently by hand with power OFF; it should turn freely without scraping.
• Verify wiring: Inspect the fan motor connector and wiring harness to the control board. Reseat connectors and look for burnt or pinched wires.
• Power test (advanced): With a multimeter and power ON (only if you are qualified), verify that the control board is sending voltage to the fan when a hot water tap is opened. If voltage is present but the fan does not run, the blower assembly likely needs replacement.
• Professional replacement: If E7 persists after clearing vents and checking wiring, have a technician replace the combustion blower and verify combustion settings.