45
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Noritz · Tankless Water Heaters
Water leak detected internally by leak sensor.
Quick Answer
Error code 45 on your Noritz Tankless Water Heaters means: Water leak detected internally by leak sensor.. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Shut off water inlet and power to unit.
2
Inspect for visible moisture and leak path.
3
Dry sensor area and reset once for test.
4
If code returns, do not keep operating the heater.
5
Schedule licensed service to locate and repair leak source.
Pro Tip
This issue typically requires professional diagnosis. Attempting this fix without proper training could cause further problems.
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