Display shows E5 and the machine shuts down shortly after starting, often with steam but little coffee.

Safety first: Unplug the coffee maker and let it cool completely before further use.

• Check water level: Ensure the Tristar reservoir is filled above the MIN mark and properly seated. Never run the machine without water.
• Descale thoroughly: Run at least one full descaling cycle. A blocked thermoblock can cause localized overheating and trigger E5.
• Allow full cool-down: Leave the unit unplugged for 30–60 minutes to allow the overheat thermostat to reset, then try again.
• Inspect thermostat (advanced): Access the heater assembly and locate the snap-disc thermostat(s) mounted on the thermoblock. Check for loose mounting screws or wiring. A thermostat that does not reset may need replacement.

Warning: Repeated E5 errors after descaling indicate a serious overheating or control issue. Continued use may be unsafe; have the unit inspected professionally.