Ariston Cooktop Error Code E.33

Error code E.33 on an Ariston cooktop indicates that the RER (rear right) cooking zone temperature sensor has been detected in an open circuit condition. An open circuit in this context means the thermistor or sensor associated with that cooking zone is no longer completing the electrical circuit, either due to a broken wire, a failed sensor element, or a disconnected connector. The cooktop's control board continuously monitors resistance values from each zone's temperature sensor, and when the resistance reading falls outside the expected range or reads as infinite (characteristic of an open circuit), the board flags this fault code and disables the affected zone as a safety measure.

The temperature sensing system on induction or ceramic cooktops uses thermistors that change resistance in a predictable way as temperature rises and falls. Under normal operation, the control board reads a specific resistance range from the RER zone sensor. An open circuit condition produces a reading that no longer corresponds to any valid temperature point, which the board interprets as a sensor failure rather than an actual temperature value. This prevents the zone from operating until the fault is resolved.

Common causes include a physically broken thermistor, a wiring harness that has developed a break or separation near the zone, or a connector that has come loose from vibration or heat cycling over time. In some cases, exposure to spilled liquids or overheating can degrade the sensor element itself, causing it to fail open. Because this fault disables the cooking zone entirely, the issue requires physical inspection and likely replacement of the sensor or associated wiring before normal operation can resume.