Unox AF04 Error Code
Communication error with the power board — the control board lost communication with the power board.
Source: Unox/Unox_XACC-0513-EPLM_ServiceManualAll_CommercialKitchen.pdf
What does Unox AF04 mean?
AF04 is a communication error between the control board and the power board. The two boards can no longer talk to each other — commonly due to a loose or faulty board-to-board cable, a problem on a connected accessory plugged into the data sockets, or insufficient power — so the oven cannot operate and stops.
Symptoms
- AF04 displayed and the oven unresponsive
- Oven does not restart normally after power cycling
- Fault appears or clears when accessory plugs are disconnected
- Connected accessories (hood, prover, deck) not powered correctly
Common causes
- Loose or open control/power board cable at the P11 socket
- Faulty plug connected to the P12 or P13 data sockets
- Oven not properly powered or a tripped circuit breaker
- Accessory fault pulling down the communication bus
- Faulty control board or power board
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Diagnostic steps
Verify supply and accessories
If accessories (hood, prover, deck) are fitted, confirm the oven is properly powered and the circuit breaker is not down.
Check the P24 socket
Verify whether the P24 socket is free; if a plug there is causing the fault, disconnect it and see if the alarm clears.
Isolate the data sockets
Disconnect any plugs from P12 and P13, restore proper connections, and check whether the oven restarts.
Test the board cable
Measure continuity pin to pin of the control/power board cable at the P11 socket with a multimeter set to ohms and restore or replace it if open.
Replace a board if needed
If the cable is good but the alarm persists, replace the control board first; if unresolved, refit the original control board and replace the power board.
When to call a professional
AF04 involves the communication wiring between two boards and possible board replacement, with accessories sharing the same bus. Continuity testing of data cables and methodical board swapping should be done by a qualified Unox technician, especially where the oven is interconnected with a hood, prover or deck.
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Other Unox Error Codes
Motor thermal protection alarm (permanent error) — the fan motor's thermal protection has tripped.
Safety thermostat alarm — the chamber safety thermostat has tripped above its limit.
Temperature probes alarm — a cooking chamber temperature probe is damaged or disconnected.
Gas alarm — a fault in the gas burner/ignition system (split into multiple AF23 conditions on later software).
Wrong position of Pollo valve.
Trolley is missing.
Tank missing or safety thermostat fault.
Chamber ceiling temperature too high.
Chamber over-temperature condition (Case 1: T > 150 °C / 302 °F; Case 2: T < 150 °C).
Single-point or multi-point core probe completely damaged.
Chamber temperature probe warning.
Front / chamber temperature probe warning.