E2
Bosch
Ignition Lockout (No Flame Detected)
Furnace displays E2 and will not fire; may indicate ignition lockout
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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
No gas supply to burner, Faulty gas valve coil, Ignition electrode not sparking, Incorrect electrode gap or wiring
How to Fix / Troubleshooting
Safety: Turn off power and gas. If you smell gas, ventilate the area and contact your gas supplier immediately.
- Gas supply check: Confirm the manual gas shutoff valve near the furnace is fully open. Verify other gas appliances work.
- Ignition electrode: Inspect the electrode and cable for cracks, carbon tracking, or loose connections. Clean and re-gap according to Bosch specifications.
- Spark test (for qualified persons only): With covers in place and observing through the sight glass, call for heat and watch for a strong spark at the electrode. If no spark is visible, the ignition transformer or control board may be faulty.
Gas valve and ignition transformer testing should be performed by a licensed technician with proper equipment.
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Repair Difficulty
Professional Required
5/5
Required Part
Ignition Electrode Assembly
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