Error Codes =========== This document lists error codes for the NWP500 heat pump water heater. .. warning:: This document describes the underlying protocol details. Most users should use the Python client library (:doc:`../python_api/models`) which handles error parsing automatically. When an error occurs, the front panel display flashes red and shows the error code. For Level 1 errors, operation continues while displaying the error. Error Code Reference -------------------- .. list-table:: :header-rows: 1 :widths: 10 10 30 50 * - Error Code - Sub Code - Reason - Self-diagnostic/Action * - E096 - 00 - Abnormal upper electric heater operation - | 1. Check the resistance of the heating element. | 2. Check the wiring of the heating element. | 3. Replace the control board. | 4. Replace the heating element. | 5. Replace the relay. | 6. Contact technical support at 1-800-519-8794. * - E097 - 00 - Abnormal lower electric heater operation - | 1. Check the resistance of the heating element. | 2. Check the wiring of the heating element. | 3. Replace the control board. | 4. Replace the heating element. | 5. Replace the relay. | 6. Contact technical support at 1-800-519-8794. * - E326 - 00 - Dry fire - Refill water until all air is expelled from the outlet and water flows. * - E407 - 01 - Abnormal hot water temperature sensor operation for lower limit - | 1. Check and reconnect the wiring. | 2. Check for disconnection in Service Mode. | 3. If there is no wiring issue, replace the temperature sensor. | • If the tank temperature sensor is faulty, operate in a reduced capacity using the opposite heating element. * - E407 - 02 - Abnormal hot water temperature sensor operation for upper limit - | 1. Check and reconnect the wiring. | 2. Check for disconnection in Service Mode. | 3. If there is no wiring issue, replace the temperature sensor. | • If the tank temperature sensor is faulty, operate in a reduced capacity using the opposite heating element. * - E445 - 01 - Abnormal mixing valve open - | 1. Replace the mixing valve. | 2. Contact technical support at 1-800-519-8794. * - E445 - 02 - Abnormal mixing valve close - | 1. Replace the mixing valve. | 2. Contact technical support at 1-800-519-8794. * - E480 - 01 - Abnormal tank upper temperature sensor operation for lower limit - | 1. Check and reconnect the wiring. | 2. Check for disconnection in Service Mode. | 3. If there is no wiring issue, replace the temperature sensor. | • If the tank temperature sensor is faulty, operate in a reduced capacity using the opposite heating element. * - E480 - 02 - Abnormal tank upper temperature sensor operation for upper limit - | 1. Check and reconnect the wiring. | 2. Check for disconnection in Service Mode. | 3. If there is no wiring issue, replace the temperature sensor. | • If the tank temperature sensor is faulty, operate in a reduced capacity using the opposite heating element. * - E481 - 01 - Abnormal tank lower temperature sensor operation for lower limit - | 1. Check and reconnect the wiring. | 2. Check for disconnection in Service Mode. | 3. If there is no wiring issue, replace the temperature sensor. | • If the tank temperature sensor is faulty, operate in a reduced capacity using the opposite heating element. * - E481 - 02 - Abnormal tank lower temperature sensor operation for upper limit - | 1. Check and reconnect the wiring. | 2. Check for disconnection in Service Mode. | 3. If there is no wiring issue, replace the temperature sensor. | • If the tank temperature sensor is faulty, operate in a reduced capacity using the opposite heating element. * - E515 - 25 - Upper electric heater relay fault - | 1. Check and reconnect the wiring. | 2. Replace the relay. * - E515 - 26 - Lower electric heater relay fault - | 1. Check and reconnect the wiring. | 2. Replace the relay. * - E515 - 27 - Compressor relay fault - | 1. Check and reconnect the wiring. | 2. Replace the relay. * - E517 - 00 - Abnormal DIP switch settings - Check and reset the DIP switch configuration. * - E593 - 00 - Abnormal panel key - Contact technical support at 1-800-519-8794. * - E594 - 00 - Abnormal EEPROM operation - Contact technical support at 1-800-519-8794. * - E595 - 00 - Abnormal power meter - | 1. Check and reconnect the wiring. | 2. Replace the power meter. * - E596 - 00 - Abnormal Wi-Fi connection - Contact technical support at 1-800-519-8794. * - E598 - 00 - Abnormal RTC (Real-Time Clock) - Contact technical support at 1-800-519-8794. * - E615 - 04 - Abnormal ADC reference voltage - | 1. Check the heating element. | 2. Check the thermistor. | 3. Replace the control board. * - E615 - 27 - Abnormal ECO feedback - | 1. Check the heating element. | 2. Check the thermistor. | 3. Replace the control board. * - E615 - 28 - Abnormal compressor feedback - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E615 - 29 - Abnormal upper heating element feedback - | 1. Check and reconnect the wiring. | 2. Replace the heating element. * - E615 - 30 - Abnormal lower heating element feedback - | 1. Check and reconnect the wiring. | 2. Replace the heating element. * - E781 - 00 - Abnormal CTA-2045 communication - | 1. Check and reconnect the wiring. | 2. Replace the module. * - E798 - 00 - Abnormal shut-off valve - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E799 - 00 - Water leak detected - | 1. Check for piping leaks. | 2. If there is a tank leak, replace the entire tank assembly. * - E901 - 00 - Abnormal ECO operation - | 1. Check the heating element. | 2. Check the thermistor. | 3. Replace the control board. * - E907 - 00 - Abnormal compressor power line connection - Check and reconnect the wiring of the compressor. * - E908 - 00 - Abnormal compressor operation - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E909 - 01 - Abnormal evaporator fan operation - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E910 - 01 - Abnormal compressor's discharge temperature sensor operation for lower limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E910 - 02 - Abnormal compressor's discharge temperature sensor operation for upper limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E911 - 00 - Abnormally high compressor's discharge temperature - Contact technical support at 1-800-519-8794. * - E912 - 01 - Abnormal compressor's suction temperature sensor operation for lower limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E912 - 02 - Abnormal compressor's suction temperature sensor operation for upper limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E913 - 00 - Abnormally low compressor's suction temperature - Contact technical support at 1-800-519-8794. * - E914 - 01 - Abnormal evaporator temperature sensor operation for lower limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E914 - 02 - Abnormal evaporator temperature sensor operation for upper limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E915 - 00 - Abnormal difference of (compressor's discharge temperature) - (compressor's suction temperature) - Contact technical support at 1-800-519-8794. * - E916 - 00 - Abnormal evaporator temperature - Contact technical support at 1-800-519-8794. * - E920 - 01 - Abnormal ambient air temperature sensor operation for lower limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E920 - 02 - Abnormal ambient air temperature sensor operation for upper limit - | 1. Check and reconnect the wiring. | 2. Contact technical support at 1-800-519-8794. * - E940 - 00 - Refrigerant line blockage - | 1. Check the electronic expansion valve (EEV) operation status for seizing. | 2. Contact technical support at 1-800-519-8794. * - E990 - 00 - Condensate overflow detected - Check for and remove any foreign objects from the condensate tubing. Error Severity Levels --------------------- **Level 1 Errors:** Level 1 errors allow the water heater to continue operating while displaying the error condition. The front panel flashes red and shows the error icon. Users can: * Press the OK button to enter error display mode * View error details in the Error History menu * Clear the error by resolving the underlying issue Level 1 errors are automatically cleared once the problem is resolved. The system continues minimal operations to maintain safety and prevent damage. Viewing Error History --------------------- The water heater stores the 10 most recent errors, with the most recent displayed at the top. To view error history: 1. Press and hold the Menu button for more than 5 seconds 2. Select "Error History" 3. Use Up/Down buttons to navigate the error list 4. Press OK to view detailed information about a specific error Each error record includes: * Error code and sub code * Date and time of occurrence * Operating conditions when error occurred Troubleshooting Tips -------------------- **Temperature Sensor Errors (E407, E480, E481, E910, E912, E914, E920):** * Verify sensor wiring connections are secure * Check for damaged or pinched wires * Use Service Mode to test sensor readings * Sensors operate within -4°F to 149°F (-20°C to 65°C) * System can operate with reduced capacity using opposite heating element if one tank sensor fails **Heating Element Errors (E096, E097, E615):** * Verify power supply: 208-240V AC, 60Hz, 1 Phase * Check element resistance with multimeter * Inspect wiring for loose connections or damage * Element specifications: 3,755W @ 208V or 5,000W @ 240V * Verify circuit breaker is 30A rated **Compressor/Heat Pump Errors (E907, E908, E911, E913, E915, E916, E940):** * Check compressor power connections * Verify proper voltage supply * Listen for unusual compressor sounds * Check refrigerant pressures (requires certified technician) * Verify evaporator fan operation * Check EEV operation and step position * Ensure adequate airflow through air intake/exhaust (Ø8") **Communication Errors (E596, E781):** * Verify WiFi signal strength (check wifiRssi in status) * For CTA-2045: Check module connection and wiring * Restart device if communication error persists * Check front panel settings menu for communication enable/disable **Water System Errors (E326, E799, E990):** * E326 (Dry fire): Ensure tank is filled before operation * E799 (Water leak): Inspect all plumbing connections and tank for leaks * E990 (Condensate overflow): Clear condensate drain tubing of obstructions **When to Contact Technical Support:** Contact technical support at 1-800-519-8794 when: * Multiple errors occur simultaneously * Error persists after following diagnostic steps * Control board or complex components need replacement * Refrigerant system work is required (certified technician only) * Safety concerns exist See Also -------- * :doc:`device_status` - Status field descriptions * :doc:`mqtt_protocol` - Error reporting via MQTT * Installation Manual - Complete technical specifications