Ariston Oven Error Code ER20
Oven temperature sensor readings are incorrect or out of expected range.
Oven temperature sensor readings are incorrect or out of expected range.
First step from the service manual
Verify sensor operation - at room temperature, resistance at terminals should be approximately 545 ohms; if OK, replace sensor; then replace power supply board.
The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.
Get the full diagnostic procedure for ER20.
- Step-by-step tests with expected resistance, voltage, and continuity values
- Wiring diagram references and connector pinouts from the OEM service manual
- Verified part numbers when replacement is required
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What ER20 means on a Ariston oven
The ER20 error code on an Ariston oven indicates that the oven temperature sensor is producing readings that fall outside the expected range. The temperature sensor, also called an NTC (negative temperature coefficient) probe or RTD sensor depending on the design, continuously reports cavity temperature to the control board. When the board receives values that are implausible, too high, too low, or erratic, it triggers ER20 and typically disables heating to prevent unsafe operation.
The primary diagnostic benchmark for this sensor is its resistance at room temperature, which should read approximately 545 ohms across its terminals. A reading significantly above or below this value confirms sensor failure. However, the wiring harness connecting the sensor to the control board is also a common culprit. Damaged insulation, corroded connector pins, or a broken wire can introduce resistance variations or open circuits that mimic a failed sensor.
If the sensor resistance checks out correctly at 545 ohms, the fault path shifts to the power supply board, which conditions and interprets the sensor signal. A failing power supply board may misread accurate sensor input or fail to supply the reference voltage needed for correct sensor operation. Diagnosis should follow the sequence: confirm sensor resistance, then replace the sensor if out of spec, and replace the power supply board only if the sensor tests acceptable.
Source: manufacturer service documentation.
Common causes of ER20
- 01
Faulty oven temperature sensor
Part replacementThe sensor itself has failed and is producing resistance values outside the expected 545 ohm baseline at room temperature. This is the most common cause and is confirmed with a simple multimeter check at the sensor terminals.
- 02
Damaged or corroded sensor wiring harness
Wiring / connectionThe wires or connector between the temperature sensor and the control board may be broken, corroded, or have degraded insulation, causing erratic or out-of-range resistance readings. Inspect the harness visually and check for continuity.
- 03
Loose or poor sensor connector connection
Wiring / connectionA partially seated or oxidized connector at either the sensor end or the board end can introduce intermittent signal faults that trigger ER20. Reseating and cleaning the connector pins may resolve the error without replacing any parts.
- 04
Faulty power supply board
Part replacementIf the sensor resistance tests correctly at approximately 545 ohms, the power supply board may be misinterpreting the signal or failing to supply the correct reference voltage to the sensor circuit. Board replacement is the next step after ruling out the sensor.
Frequently asked questions about ER20
What does ER20 mean on a Ariston oven?
Can I fix ER20 on my Ariston oven myself?
Is it safe to use my Ariston oven when ER20 is displayed?
Will resetting my Ariston oven clear the ER20 error?
How much does it cost to repair an Ariston oven showing ER20?
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