Bosch Overheating / Electrical or Combustion Fault

Bosch water heater emits a burning smell or visible smoke from the unit

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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

Dust or debris burning off heat exchanger, Electrical component overheating, Sooting due to improper combustion, Melted wiring insulation

How to Fix / Troubleshooting

Safety first: Immediately turn OFF power at the breaker and close the gas valve. If you see flames or heavy smoke, evacuate and call emergency services.

  • Visual inspection: After the unit cools, remove the cover and look for burned wiring, discolored components, or soot buildup.
  • Clean dust: Light dust on the heat exchanger can cause temporary odor on first startup. Gently vacuum dust from accessible surfaces.
  • Check wiring: Inspect for melted insulation or burned connectors. Do not operate the heater until damaged wiring is repaired.
  • Combustion issues: Soot or a strong burning smell from the exhaust indicates improper combustion. A qualified technician must adjust gas pressure, check venting, and clean the burner.
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Repair Difficulty

Professional Required 5/5

Required Part

Wiring Harness
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