H07
Bosch
Outlet Temperature Sensor Fault (Electric Model)
Bosch electric tankless water heater shows H07 and does not heat water
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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
Failed outlet NTC sensor, Loose sensor wiring, Sensor shorted due to moisture, Defective control board input
How to Fix / Troubleshooting
Safety first: Turn OFF power at the breaker. Electric tankless heaters contain live high-voltage components even when not heating.
- Access sensor: Remove the front cover and locate the outlet temperature sensor on the hot water outlet manifold.
- Inspect wiring: Check the sensor connector and wiring for signs of moisture, corrosion, or damage. Dry any moisture and reseat the connector.
- Measure resistance: With power off, disconnect the sensor and measure its resistance. Compare to the Bosch specification chart. Replace the sensor if out of range.
- Control board check: If a new sensor does not clear H07, the control board may be faulty and should be replaced by a qualified technician.
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Repair Difficulty
Medium
3/5
Required Part
Outlet Temperature Sensor (NTC)
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