Unox AF23 Error Code

What does Unox AF23 mean?

AF23 is the main gas-system alarm on gas ovens, raised when the burner fails to operate correctly — for example the gas valve does not open, or no flame is detected when it should be. From software version 24570 (June 2016) the alarm was split into multiple AF23 conditions covering cooking, washing and pre-heating phases, distinguishing valve-open versus no-flame states.

Symptoms

• AF23 shown on the control panel of a gas oven
• Burner fails to light or flame is lost during a cycle
• Oven does not reach or hold temperature
• Repeated ignition attempts before the alarm appears

Common causes

• Gas valve not opening during cooking, washing or pre-heating
• No flame detected after the valve opens
• Loose burner mounting or gas circuit assembly fault
• Ignition or flame-detection (flame control board) fault
• Gas supply problem upstream of the appliance

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Diagnostic steps

1. Confirm gas supply

   Verify the gas supply to the appliance is on and at the correct pressure before investigating the oven itself.

2. Identify the AF23 sub-condition

   On software 24570 or later, note which phase (cooking, washing, pre-heating) and whether the valve opened and flame was detected, as the manual maps these to specific AF23 alarms.

3. Inspect the gas mechanical system

   Check the burner-to-heat-exchanger mounting and gas circuit per the maintenance section; later units use two studs with locking bars instead of three.

4. Check ignition and flame detection

   Verify the ignition and flame-control board operation so a flame is detected when the gas valve opens.

5. Escalate to gas service

   If the burner still fails to light or hold flame, have a qualified gas technician complete the gas fumes test and burner setup.

When to call a professional

AF23 is a gas-combustion fault. Work on the burner, gas valve, flame detection and combustion setup must be done by a technician qualified to service gas appliances, including the gas fumes (CO/CO2) test. Do not attempt to clear repeated gas alarms yourself; isolate the appliance and call qualified gas service.