Ariston Oven Error Code ER78

ER78 indicates a Key5 fault on the Ariston oven's touch control panel, meaning the fifth touch button has been detected as malfunctioning. The control board monitors all touch inputs continuously and flags this code when Key5 produces an unexpected or invalid signal. Moisture from cooking is the most common cause, but a missing inductive rubber contact piece or a failed display board can also be responsible.

ER78 relates to a touch button fault on the control panel rather than a heating or gas system failure, so the immediate safety risk is limited. However, a malfunctioning control interface could prevent you from adjusting settings or shutting off functions reliably. It is advisable to avoid extended use until the fault is diagnosed and resolved.

If the fault is caused by condensation alone, there is no parts cost involved. Replacing an inductive rubber contact piece, if available separately, would be a low-cost repair, typically in the range of a few dollars for the part plus labor. A full display board replacement is the most expensive scenario, with parts and labor costs commonly ranging from around 100 to 300 dollars depending on the specific model and technician rates in your area.

The first step is something any user can do: open the oven door and allow time for condensation to dry from the touch panel, then check if the error clears on its own. If it persists, inspecting the inductive rubber contact pieces requires opening the panel area, which is best handled by a technician. Replacing the display board is also a technical repair that involves working with internal wiring and components.

A power reset may temporarily clear the display, but if the underlying cause, such as moisture, a missing rubber contact piece, or a faulty display board, has not been addressed, the ER78 code is likely to return. Drying the panel thoroughly before resetting gives the best chance of a lasting resolution without parts replacement.