Ariston Oven Error Code ER91

ER91 indicates a fault on Key18 of the touch control panel. The oven's control system has detected that this specific touch button is malfunctioning, either failing to respond or registering incorrect input. The cause is commonly moisture on the touch surface, a dislodged inductive rubber contact piece, or a failed display board.

It is generally not advisable to continue using the oven while a control panel fault code is active. A malfunctioning touch button could affect your ability to set temperatures or cancel cooking cycles reliably. Wait for the fault to clear after drying, or have the oven serviced before further use.

If the fault is caused purely by condensation, there is no parts cost involved. If the inductive rubber contact pieces need replacement, costs are typically low. Replacing the display board is the most expensive scenario, with parts and labor costs generally ranging from around 100 to 250 dollars or more depending on your region and the technician's rates.

In many cases, yes. Start by opening the oven door and waiting for any condensation to evaporate fully from the touch panel surface. If the fault clears after drying, no further action is needed. If the fault persists, checking and reseating the inductive rubber contact pieces is a possible next step, though accessing them requires removing the control fascia. Replacing the display board is best handled by a qualified technician.

A power reset by switching off the oven at the circuit breaker for several minutes may temporarily clear the fault, but if the underlying cause is a failed display board or damaged rubber contact piece, the code will return. A reset alone is only a lasting fix if the fault was triggered by a temporary moisture event that has since resolved.