Unox AF02

What does Unox AF02 mean?

AF02 is the safety thermostat alarm. The oven's safety thermostat, which trips around 320 °C (608 °F), has opened because the cooking chamber overheated, and the oven is locked in STOP. It protects the appliance when the normal temperature control fails to limit chamber temperature.

Symptoms

• AF02 displayed and the oven stops heating
• Chamber reaching abnormally high temperature before the trip
• Heating elements appear to stay energised
• Alarm returns after a reset attempt

Common causes

• Safety thermostat triggered by genuine overheating
• Contactors stuck closed, feeding the heating elements constantly
• Chamber probe 1 swapped with chamber probe 2
• Poor oven installation or an external heating source
• Power board damaged
• Open wiring between the P22 socket and the thermostat

Diagnostic steps

1. 01

   Let the oven cool and reset the thermostat

   Wait for the oven to cool, reset the thermostat, and consider causes such as installation, external heat sources and swapped chamber probes.

2. 02

   Check for stuck contactors

   Verify the contactors are not stuck closed feeding the heating elements constantly, which causes uncontrolled heating.

3. 03

   Test the thermostat continuity

   Disconnect the P22 socket from the contactor and test continuity between pins 4 and 5 (TSA and TSR labels on the power board) with a multimeter set to ohms.

4. 04

   Test the thermostat and wiring

   Measure continuity of the safety thermostat itself, then pin to pin from the P22 socket to the thermostat plug; replace the thermostat or restore the cable harness as needed.

5. 05

   Replace the power board

   If the alarm persists after the above, replace the power board and send the UNOX service department a picture as instructed.

When to call a professional

AF02 means a safety device tripped to prevent an over-temperature condition. Diagnosing stuck contactors, swapped probes and a possibly faulty power board requires mains-voltage testing and Unox-specific knowledge of the board labelling. Have a qualified technician investigate; never bypass or disable the safety thermostat to keep cooking.