Display shows E1 and brewing will not start or stops immediately on Oster programmable coffee maker.

Safety first: Unplug the coffee maker and let it cool completely before opening any panels. Never work on the unit while it is connected to power.

Step-by-step checks:

• Power reset: Unplug the coffee maker for 10–15 minutes, then plug it back in and try a brew cycle. Sometimes the control board will clear a transient E1 error after a full power reset.
• Inspect the warming plate area: Turn the unit over (on a towel) and look for any obvious damage or burn marks under the warming plate area where the temperature sensor is mounted.
• Check sensor wiring (if accessible): Remove the bottom cover (usually Phillips screws). Locate the small sensor clipped to the underside of the warming plate or boiler tube with two thin wires going to the control board. Make sure the connector is fully seated and there are no broken or pinched wires.
• Clean corrosion: If you see light corrosion on the sensor connector, disconnect it (with the unit unplugged), clean the contacts with electrical contact cleaner or isopropyl alcohol, let dry, reconnect, and reassemble.
• Test with a multimeter (advanced): With the sensor disconnected, measure its resistance at room temperature. A typical NTC sensor will read between 5–100 kΩ depending on design. If it reads open (OL) or 0 Ω, the sensor is defective and must be replaced.

When to replace parts: If wiring is intact and the E1 code persists, replace the temperature sensor (NTC). If a new sensor does not clear the error, the main control board is likely faulty and should be replaced or the machine should be serviced by a professional.