How a Viking microwave signals trouble
A Viking microwave does not show diagnostic F-codes — its display uses plain word prompts and otherwise behaves in observable ways, so a Viking microwave repair is symptom-led. The word prompts are guidance, not fault numbers: WELCOME appears after power is restored, ERROR shows after an invalid clock entry, and on a convection or defrost program you may see ERROR WEIGHT TOO SMALL or ERROR WEIGHT TOO LARGE. Recognising that these are prompts rather than failures saves an unnecessary service call.
The prompts that are not faults
Several displays are normal. WELCOME after a power cut simply means the clock needs setting; an ERROR on the clock means the time entry was invalid; and the weight-too-small or weight-too-large messages on auto-defrost mean the entered weight is outside the program range. Clearing the prompt or re-entering the value resolves these. They are not codes pointing at a failed part, and no technician is needed for them.
The symptoms that lead diagnosis
Real microwave faults are read from behaviour. A microwave that is dead with no power, that will not start (most often a door-interlock switch — the single most common cause), that runs but will not heat (the magnetron, the high-voltage diode or the capacitor), that has a turntable not turning, or that sparks or arcs inside is diagnosed from the symptom. On an over-range VMOR the hood fan or cooktop light may fail independently of the microwave, and a VMOD DrawerMicro that will not open points at its drawer mechanism. Sparking or arcing usually traces to a damaged waveguide cover or metal in the cavity.
What to check, and when to call
For a no-start, confirm the door closes fully and latches, since the interlock must be made; for an arcing complaint, remove any metal and check the waveguide cover. A microwave that is dead, runs but will not heat, sparks internally, has a turntable that will not turn, or a drawer that will not open needs an experienced, independent technician with genuine parts — the high-voltage components inside store a dangerous charge and are not a DIY repair. Browse the microwave diagnostics page or the wider error codes library, then book microwave repair. Confirm your model on the manufacturer’s site at vikingrange.com.