Oven does not reach set temperature; preheat takes excessively long or never completes. Display may show E03 after some time.

Safety first: Disconnect power at the breaker. Confirm no voltage is present before working.

• Test upper and grill elements: Remove the rear panel of the oven. Identify the upper and grill element terminals. Disconnect one wire from each and measure resistance with a multimeter. Typical values are 15–40 Ω. Replace any element that reads open or shows visible bulging or hot spots.
• Check terminal block: Inspect the main power terminal block where the mains cable enters the oven. Look for heat damage, loose screws, or carbonization. Tighten connections and replace the block if melted or cracked.
• Inspect wiring harness: Follow the wires from the terminal block to the elements and PCB. Repair any burnt or brittle wires using high-temperature oven cable and proper crimp connectors.
• Relay inspection: On the main PCB, locate the relays controlling the upper and grill elements. Look for burn marks or cracked solder joints. If a relay is visibly damaged or does not click when heating should be active (requires live testing by a qualified person), the PCB or relay must be replaced.
• Re-test: After replacing any faulty parts, reassemble, restore power, and test preheat in conventional and fan-assisted modes. If E03 persists, a deeper PCB diagnosis by a technician is advised.