ao-smith NNLP-199-H NG Tankless Water Heater Error Codes
NNLP-199-H NG Error Code Reference
Section titled “NNLP-199-H NG Error Code Reference”Natural gas, 11 GPM, condensing
| Error Code | Fault Description |
|---|---|
| E1 | No ignition — burner failed to light |
| E5 | Insufficient water flow or flow sensor fault |
| E7 | Exhaust / flue blockage or temperature sensor fault |
| E9 | Outlet water temperature limit exceeded |
| E10 | Combustion air fan motor fault |
| E11 | Cold inlet thermistor (NTC1) fault |