Safety first: Isolate the oven from the mains before any disassembly.

Steps to check:

Locate the oven temperature sensor (NTC probe) inside the cavity, usually at the rear upper area secured with 2 screws.
Remove the screws and gently pull the sensor forward to access the connector or wiring.
From the rear or top of the oven, trace the sensor wires to the main control board. Check for cuts, burns, or disconnections.
Use a multimeter (ohms range) to measure resistance across the sensor leads. A typical Gram oven NTC is around 500–1100 Ω at room temperature (exact value varies by model). If the meter shows OL (open) or 0 Ω (short), the sensor is faulty.
Reseat the connector on the main PCB and inspect for burned or cracked solder joints at the sensor input.
If wiring and PCB look intact but E1 remains, replace the oven temperature sensor with a Gram-compatible NTC probe.

Warning: Never test resistance with power connected. If you lack a meter or are unsure of readings, seek professional service.

Oven displays E1 and does not heat or immediately stops the program.

Possible Causes