Machine shows E09 and does not heat water; coffee is cold or not dispensed.

Safety first: Unplug the appliance. Heating circuits carry mains voltage; only qualified persons should test live circuits.

• Power reset: Disconnect power for 5–10 minutes, then reconnect and test. If E09 returns immediately, a hardware fault is likely.
• Check for descaling need: If the machine has been heavily scaled, the heater may have overheated. Run a descaling cycle if the machine will allow it, but do not expect this to fix a failed heater.
• Advanced electrical check (for trained users): With covers removed and the unit unplugged, inspect the thermoblock for burnt spots, loose connectors, or a tripped thermal fuse. Use a multimeter to check continuity of the heater and thermal fuse.
• If heater is open or fuse blown: The thermoblock assembly or thermal fuse must be replaced. This involves working with mains wiring; if you are not experienced, contact Bosch service.