Breville coffee maker displays ER05 and will not start; sometimes accompanied by beeping.

Safety: Disconnect power before manipulating the tank area if you will be removing covers.

Basic checks:

• Reseat the tank: Remove the water reservoir, rinse it, and firmly reseat it until it clicks or sits flush.
• Clean the tank: Remove scale and slime from the tank, especially around the float. Ensure the float moves freely up and down.
• Check magnet: Verify the float's magnet is still present and not corroded. If the float is waterlogged or stuck, replace the reservoir.

Sensor inspection (advanced):

• Locate the reed switch or electronic level sensor near the tank area inside the machine.
• Inspect for corrosion or broken wires. Clean any mineral deposits with isopropyl alcohol and a cotton swab.
• Test the reed switch with a multimeter while moving a magnet near it; it should open/close as the magnet passes.

Resolution: Replace the water reservoir if the float or magnet is defective. If the tank is good but ER05 persists, replace the reed switch/level sensor assembly or have a technician test and replace the sensor or control board input.