Microwave runs but does not heat; display shows F03 after a few seconds of operation.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Critical safety warning: The high‑voltage section of a microwave (transformer, capacitor, diode, magnetron) operates at thousands of volts and can be fatal. Do not attempt to test or replace these parts unless you are a trained appliance technician with proper tools and procedures.
- Step 1 – Confirm symptom: Place a cup of water inside and run for 1–2 minutes. If the turntable and light work but the water remains cold and F03 appears, the control is detecting a heating fault.
- Step 2 – Basic external checks: Ensure the unit is on a dedicated outlet and not on an overloaded extension lead. Low supply voltage can sometimes trigger heating errors.
- Step 3 – Internal inspection (visual only for non‑experts): With the unit unplugged and cover removed, visually inspect the high‑voltage area for obvious burning, melted insulation, or a split capacitor casing. Do not touch or short the capacitor.
- Step 4 – Professional diagnosis: A technician will discharge the capacitor, then test the magnetron, HV diode, capacitor, and transformer with a multimeter and insulation tester. The faulty component is then replaced with the correct Indesit spare.
Recommendation: Due to the danger and complexity, F03 faults should be handled by an authorised Indesit service centre.