If the error only appears intermittently after the machine heats up, limescale may be the culprit. If the machine allows you to navigate the menu before the error locks the screen, run a thorough descaling cycle using Krups descaling powder or a food-safe alternative. This removes mineral insulation from the heating element. 3. Inspecting Internal Connections (Advanced)

This is the most common reason for the error. The NTC sensor itself might be broken and need replacement. Alternatively, the thin wires connecting the sensor to the main control board might have come loose or suffered a poor connection. One technician described an instance where the connectors for the sensor had completely cracked.

To confirm the NTC sensor is functioning, you can measure its resistance.

Less common, but the main power board might fail to receive the signal. Step-by-Step Troubleshooting for Error 09

If the machine allows you to navigate the menu before the error code locks the screen, run a intensive descaling cycle using official Krups descaling powder. Limescale acts as an insulator; removing it can restore proper thermal conductivity between the thermoblock and the NTC sensor.

The heating element itself can burn out over time due to heavy usage or severe limescale insulation, leaving it unable to heat water.