F7
Junkers
Flame Signal Error / Flame Present at Wrong Time
F7 appears; unit may lock out after ignition attempts, sometimes with delayed ignition or small bangs.
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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.
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Possible Causes
Ionization electrode sensing false flame, Gas valve leaking slightly when closed, Control board flame circuit fault, Strong electrical interference on ionization cable
How to Fix / Troubleshooting
Safety: This fault can indicate unsafe gas valve behavior. Do not continue to reset the unit repeatedly.
- Inspect ionization cable: Ensure the cable is not damaged, touching metal edges, or routed near high-voltage ignition cables.
- Clean electrode: Remove soot and oxidation from the ionization rod and ensure correct gap and position.
- Observe ignition: With the cover on, watch through the inspection window (if present). Any delayed ignition or small explosions require immediate professional attention.
- Call service: If F7 repeats, a technician must test the gas valve tightness and control board. Do not attempt gas valve repairs yourself.
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Repair Difficulty
Professional Required
5/5
Required Part
Ionization Electrode or Gas Valve
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