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Error code reference

Ariston Oven Error Code ER91

Key18 fault on Touch control

Ariston codesAriston oven codes

Key18 fault on Touch control — touch button malfunction.

First step from the service manual

Open door, wait for condensation to dry; if fault persists and all inductive rubber pieces are present, replace display board.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What ER91 means on a Ariston oven

ER91 is a touch control fault code specific to Key18 on the Ariston oven's capacitive touch interface. The touch control board uses inductive rubber contact pieces beneath each button zone to register user input. When Key18 fails to respond correctly, either registering a phantom press or becoming unresponsive, the control system logs ER91 and may lock out oven operation to prevent unintended behavior.

The most frequent trigger for this fault is moisture or condensation on the touch panel surface. Steam generated during cooking can settle on the glass or seep behind the control fascia, temporarily disrupting the capacitive sensing layer and causing a false fault reading. This is why the first diagnostic step is to open the oven door and allow the condensation to fully evaporate before drawing conclusions about component failure.

If the fault persists after the panel has dried completely, the next area to inspect is the physical condition of the inductive rubber pieces behind the touch surface. These small rubber components transmit capacitive input from the button zone to the PCB. If any are dislodged, compressed, or missing, Key18 will not function correctly. When all rubber pieces are confirmed present and correctly seated and the fault remains active, the display board itself has failed and must be replaced to restore proper touch control function.

Source: manufacturer service documentation.

Common causes of ER91

  1. 01

    Condensation or moisture on the touch panel

    Wiring / connection

    Steam from cooking can settle on or behind the touch panel and disrupt the capacitive sensing for Key18. Open the oven door, allow the panel to dry thoroughly, and check whether the fault clears on its own.

  2. 02

    Dislodged or missing inductive rubber contact piece

    Wiring / connection

    Each touch button zone relies on a small inductive rubber piece to transmit input to the board. If the rubber piece behind Key18 has shifted out of position or is missing, the button will not register correctly.

  3. 03

    Failed or damaged display board

    Part replacement

    If condensation has dried, all rubber contact pieces are confirmed present and seated, and the ER91 fault remains active, the touch control display board itself has failed and requires replacement.

  4. 04

    Contamination on the touch surface

    Wiring / connection

    Grease, food residue, or cleaning product film on the touch panel glass can interfere with capacitive touch detection and trigger a Key18 fault. Clean the panel surface gently with a dry or lightly damp cloth.

See the test procedure for each cause

Frequently asked questions about ER91

What does ER91 mean on a Ariston oven?
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.
Can I fix ER91 myself without calling a technician?
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.
Is it safe to use my Ariston oven while ER91 is displayed?
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.
Will resetting the oven clear the ER91 error code?
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.
How much does it cost to repair an Ariston oven with an ER91 fault?
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.

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