Ariston Cooktop Error Code E.31

Error code E.31 on an Ariston cooktop indicates that the REL (relay-controlled) cooking zone temperature sensor has been detected in an open circuit condition. This means the control board is receiving no signal from the temperature sensor assigned to that cooking zone, which is equivalent to an infinitely high resistance reading across the sensor terminals. Temperature sensors used in induction and electric cooktops are typically NTC (negative temperature coefficient) thermistors, which change resistance predictably as temperature rises and falls. An open circuit means the electrical path through the sensor has been completely broken, and the board cannot interpret any temperature data for that zone.

The temperature sensor in a cooktop cooking zone serves a critical safety and performance function. It continuously feeds temperature data back to the main control board, which uses this information to regulate power output, prevent overheating, and protect both the cooking surface and the internal electronics. When the control board detects an open circuit on this sensor line, it disables the affected cooking zone entirely as a safety measure to prevent uncontrolled heating.

The most common physical causes of an open circuit condition include a broken or disconnected sensor wire harness, a failed thermistor element inside the sensor itself, or damage to the sensor connector at the board or sensor end. Physical stress from heat cycling over time can cause wire insulation to crack and conductors to break. In some cases, the main control board's sensor input circuit may itself be damaged, though this is less common than a failed sensor or wiring fault.