Bunn digital brewer shows E03 and will not brew; sometimes occurs after a dry-fire or overheating event.

Safety: Unplug the brewer. Allow at least 30–45 minutes for the tank to cool. Do not attempt to reset a hot thermostat.

Steps:

• 1. Confirm water level: Ensure the internal tank is properly filled. On plumbed-in Bunn models, verify water supply is on and inlet screen is not clogged. On pour-over models, ensure you have primed the tank per the manual.
• 2. Access high-limit: Remove the rear or top cover to access the hot water tank. The high-limit thermostat is usually a small round or rectangular device mounted directly to the tank with two wires.
• 3. Reset thermostat: Many Bunn high-limits have a small red or black reset button. Press it firmly until you feel a click. If it immediately trips again, do not keep resetting—find the cause of overheating.
• 4. Check continuity: With power disconnected, test across the thermostat terminals with a multimeter. It should show continuity when reset. If it remains open, replace the high-limit thermostat.
• 5. Inspect heater control: If the thermostat repeatedly trips, the heater may be stuck on due to a welded relay on the control board or a shorted heater. Inspect the control board and heater wiring for damage.
• 6. Clear error: After resetting or replacing the thermostat, reassemble, plug in, and allow the unit to heat. The E03 code should clear automatically on many models after a successful heat cycle.

Warning: Never bypass or short the high-limit thermostat; it is a critical safety device.