Display shows E3 and brewing stops shortly after starting on Oster digital coffee maker.

Safety first: Unplug the coffee maker and let it cool before handling.

External checks:

• Check water level: Ensure the water reservoir is filled above the minimum mark and properly seated.
• Inspect reservoir outlet: Remove the reservoir (if removable) and inspect the outlet port for debris, coffee grounds, or scale. Rinse thoroughly.

Descale the water path:

• Fill the reservoir with a 1:1 mixture of white vinegar and water.
• Start a brew cycle and allow about half the solution to run through.
• Turn the unit off and let it sit for 20–30 minutes to dissolve internal scale.
• Restart and complete the cycle, then run 2–3 full reservoirs of clean water to rinse.

Internal inspection (if E3 persists):

• Remove the bottom cover to access the aluminum heating tube and any flow sensor or one-way valve.
• Check silicone hoses for kinks or blockages.
• If a flow sensor is present (small plastic housing with wires in the water line), ensure its connector is firmly seated on the control board.

If descaling and hose inspection do not clear the E3 error, the flow sensor or control board may need replacement.