Unox AL03 Error Code
Prover lack of power alarm.
Source: Unox/Unox_XACC-0513-EPLM_ServiceManualAll_CommercialKitchen.pdf
What does Unox AL03 mean?
AL03 is a lack-of-power alarm on the prover accessory. The prover is not receiving the electrical supply it needs to operate, so it raises this alarm. The main oven can still be used while the prover is unavailable until power is restored.
Symptoms
- AL03 shown referencing the prover
- Prover does not operate
- Main oven still usable
- Alarm persists until power is restored
Common causes
- Prover not powered or its supply tripped
- Loose or open power connection to the prover
- Circuit breaker for the prover down
- Prover power board fault
Ask the AskWhiz AI about Unox AL03
AskWhiz
online
Diagnostic steps
Check the prover supply
Confirm the prover is powered and its circuit breaker is not tripped.
Inspect the connection
With power off, check the power connection between the oven and the prover is secure.
Test the supply
Measure the prover supply voltage with a multimeter to confirm power is present.
Service the board
If power is present but the prover does not run, have the prover power board checked.
When to call a professional
AL03 affects the prover accessory. A supply check may be simple, but testing the power connection and board involves mains-voltage work for a qualified Unox technician if power is present yet the prover stays off.
Stop searching through PDFs. Our AI assistant on WhatsApp is trained on official Unox documentation and can diagnose this fault code and guide you through the repair in minutes.
5 free questions per bot in your browser — no signup.
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.
Communication error with the power board — the control board lost communication with the power board.
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.