Safety: Disconnect from mains. High voltages are present even when the oven is off.

Check basic operation: Confirm that the oven light and fan operate. If only heating is missing and E003 is shown, the fault is likely in the heating circuit.
Inspect wiring: Remove the rear panel. Check connectors to the top grill element and bottom element for signs of burning, discoloration, or looseness. Reseat any loose connectors firmly.
Test elements: With wires disconnected, measure resistance of each heating element. A typical Siemens element is 20–60 Ω. Infinite resistance indicates a failed element.
Check supply to elements: If comfortable and qualified, test for mains voltage at the element terminals when a heating program is started (extreme caution). No voltage with E003 suggests a relay or control board issue.
Board inspection: Remove the control module cover and inspect for burnt relay contacts, cracked solder joints, or charred areas. If present, the module usually needs replacement rather than repair.

Oven does not heat, E003 appears shortly after start, grill and bottom heat both inoperative

Possible Causes