Ascaso coffee machine displays E3 and stops heating; temperature overshoots or machine shuts down for safety.

Safety first: Unplug the machine and allow it to cool completely. Do not bypass safety thermostats or fuses.

Steps to address E3:

• Inspect external thermostats: Remove the top cover and locate the manual-reset thermostat or thermal cutout on the boiler. Some Ascaso models have a small red reset button on the thermostat. Press gently to reset if tripped.
• Check for limescale: Heavy scale on the boiler can cause hot spots. If the machine has not been descaled regularly, perform a full descaling using an Ascaso-approved descaler, following the user manual.
• Test thermostats and thermal fuses: With the machine unplugged, disconnect the thermostat/thermal fuse and check continuity with a multimeter. An open reading on a non-resettable fuse means it must be replaced.
• Inspect wiring and terminals: Look for burnt connectors on the boiler, thermostats, and control board. Replace any heat-damaged terminals and ensure tight connections.
• Evaluate control board: If the boiler continues to overheat or E3 recurs after replacing thermostats and descaling, the heating triac or relay on the control board may be stuck on. In that case, replace the main control board.

Warning: Never bypass a thermal fuse or thermostat. Doing so can cause fire or severe damage.