Furnace displays E2, burner stops, sometimes after running for a short period.

Safety first: Isolate power and gas. Allow the unit to cool before opening the combustion chamber.

• 1. Clean burner and electrodes: Remove the burner assembly following Junkers instructions. Clean burner surfaces and ports with a soft brush. Clean the ionization electrode with a fine abrasive pad and check for cracks.
• 2. Check grounding: Verify that the furnace has a solid earth connection. Loose or corroded earth terminals can cause unstable flame detection. Tighten and clean all earth points.
• 3. Gas pressure and quality: Have a technician check that gas pressure is within specification and that combustion is correctly adjusted. Low pressure or an incorrect gas type can cause flame instability.
• 4. Replace ionization electrode if needed: If the electrode is worn, cracked, or heavily corroded, replace it with an original Junkers part.
• 5. Monitor operation: After reassembly, run the furnace and observe flame stability through the inspection window. If E2 recurs, further combustion analysis by a professional is required.