Induction or ceramic cooktop shows E1 and the selected zone will not heat.

Safety first: Isolate the cooktop from mains power at the breaker. Wait for all hot surface indicators to go off before proceeding.

• Check for overheating or blocked ventilation: Ensure the ventilation openings under the cooktop are not blocked by drawers or items. Remove any obstructions and allow the unit to cool for 30 minutes, then test again.
• Access the underside: Remove the cooktop from the worktop if necessary (release mounting clips) and place it on a soft surface. Remove the bottom cover to expose the power modules.
• Locate the NTC sensor: Each induction or radiant zone has a small temperature sensor (NTC) attached to the underside of the glass or coil. Inspect the sensor and its wiring for damage or disconnection.
• Test the sensor: Using a multimeter set to resistance, measure the NTC at room temperature. Compare the reading to the service data for your Gram model (typically 50–200 kΩ at 25°C). Infinite or near-zero resistance indicates a faulty sensor.
• Replace if necessary: If the NTC is defective, replace it with the correct Gram temperature sensor for that zone. Reassemble the cooktop and test. If E1 remains on the same zone, the power module PCB may need replacement.

Warning: Internal components can retain charge even when unplugged. Discharge capacitors and avoid touching live tracks. If unsure, call a professional.