Rheem Water Heater Error Codes Explained
What the A-series alerts on a Rheem hybrid water heater actually report, straight from Rheem’s own technical service bulletin.
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Which Rheem Water Heaters Display Error Codes?
Rheem Generation 4 heat pump water heaters report A-series alert codes, and Rheem publishes separate troubleshooting bulletins for its conventional gas and electric tanks and its electric tankless units. Knowing which family your unit belongs to tells you which bulletin applies.
Rheem publishes technical service bulletins for each product family. The alert codes below are taken from the heat pump water heater Generation 4 troubleshooting bulletin. Source: Rheem Water Heater Technical Bulletins, bulletin 1330, accessed 2026-09-16.
We service Rheem equipment across Harrisburg City, and the brand-specific service page is Rheem Water Heater Repair in Harrisburg, PA.
What Do the Rheem A-Series Alert Codes Mean?
The A-series codes group into four families: sensor (thermistor) failures, compressor shutdowns, element and relay errors, and safety alarms. The table below lists the codes as Rheem names them in bulletin 1330.
| Code | What Rheem calls it | Family |
|---|---|---|
| A001 | Configuration Data Restore Failure | Control board |
| A004 | Comp. Shutdown: Discharge-Suction Trip | Compressor |
| A005 | Compressor Shutdown: Discharge Temp High | Compressor |
| A006 | Compressor Shutdown: Suction Temperature Low | Compressor |
| A007 | Compressor Shutdown: Hi Press. Switch Trip | Compressor |
| A008 | Detected Dry Fire Condition | Safety |
| A101 | Suction Temperature Thermistor Failure | Sensor |
| A102 | Ambient Temperature Thermistor Failure | Sensor |
| A103 | Lower Heater Temp Thermistor Failure | Sensor |
| A104 | Upper Heater Temp Thermistor Failure | Sensor |
| A105 | Evaporator Temp Thermistor Failure | Sensor |
| A106 | Discharge Temp Thermistor Failure | Sensor |
| A107 | Water Leak Detected | Safety |
| A110 | Lower Temperature Conversion Stuck Error | Control board |
| A125 / A126 | Lower/Upper Element Error or Relay Stuck Closed | Element and relay |
| A128 / A129 | Lower/Upper Element Relay Failure to Close Error | Element and relay |
| A200 | Emergency Cut Off (ECO) Alarm | Safety |
The bulletin lists further conversion-error codes beyond those shown here. Where your display shows a code that is not in this table, the model-specific bulletin for your unit is the authority.
What Should You Do When a Rheem Code Appears?
Write the code down, note whether the unit is still making hot water, and give both to the technician — those two facts help narrow the fault before anyone arrives.
What does a sensor code mean?
A thermistor code reports that one temperature sensor is reading as a short or an open circuit. For thermistor faults, Rheem’s bulletin states that the compressor remains locked out for the rest of the heat demand and the electric heating elements complete the current heating cycle. That is why a unit showing a sensor code can still be delivering hot water.
What does a compressor shutdown mean?
A compressor shutdown code means the refrigerant circuit protected itself. Rheem names these individually — discharge temperature high, suction temperature low, high pressure switch trip — which points a technician at a specific measurement rather than a general fault. Rheem’s bulletin also states that the control energizes the electric elements, which substitute for the compressor until the fault clears. The refrigerant circuit is sealed, and work on equipment that could release refrigerant is regulated by the EPA under Section 608 of the Clean Air Act. Source: US EPA, Section 608 of the Clean Air Act, accessed 2026-09-17.
What does an element or relay code mean?
These report a problem in the electric backup side: an element fault, or a relay that is stuck closed or failing to close. A relay stuck closed is worth attention quickly, because it can mean the element is energized when it should not be.
What does the ECO alarm mean?
The emergency cut off alarm reports that the ECO safety device has operated. That is a safety trip, not a nuisance code, and it needs the cause established rather than the device reset and forgotten.
Leave panel work to a technician. These units carry 240 volt connections and a sealed refrigerant circuit, and the diagnostic steps in Rheem’s bulletin are written for a service technician rather than a homeowner.
What About Rheem Tankless and Conventional Tank Models?
Rheem documents its electric tankless units with a sequence-of-operations troubleshooting bulletin, and publishes separate troubleshooting bulletins for its conventional gas and electric tanks.
Rheem’s electric tankless bulletin walks through the sequence: primary power at the breaker, the energy cut off, whether the elements are being powered, whether the elements read correctly, and whether the thermistor is sensing incoming water temperature. The same bulletin notes that a Rheem electric tankless unit needs a minimum flow to activate at all, which is why a low-flow fixture can look like a dead unit. Source: Rheem technical service bulletin 8501, accessed 2026-09-16.
For on-demand units generally, our Tankless Water Heater Repair in Harrisburg, PA page covers the diagnostic process and the error-code approach across brands. For a Rheem hybrid, Heat Pump Water Heater Repair in Harrisburg, PA covers the service scope.
Frequently Asked Questions About Rheem Error Codes
What does A107 mean on a Rheem water heater?
Rheem names code A107 Water Leak Detected in its Generation 4 heat pump water heater troubleshooting bulletin. It reports that the unit has detected water where it should not be, which needs investigating rather than clearing.
What does the A200 code mean on a Rheem hybrid?
Rheem names A200 the Emergency Cut Off (ECO) Alarm. It reports that the ECO safety device has operated, so the cause needs establishing rather than the device simply being reset.
Why is my Rheem hybrid still making hot water with an error showing?
For thermistor faults and several compressor faults, Rheem states that the compressor is locked out and the electric heating elements take over the heating. The unit keeps delivering hot water while the heat pump side is out of action.
Do these A-series codes apply to Rheem gas and electric tanks?
No. The A-series codes described here come from the Rheem Generation 4 heat pump water heater bulletin. Rheem publishes separate troubleshooting bulletins for its conventional gas and electric tanks.
Can I clear a Rheem error code myself?
Clearing the display does not address what produced the code. These units carry 240 volt connections and a sealed refrigerant circuit, and Rheem writes its diagnostic steps for a service technician rather than a homeowner.
Where can I find the official Rheem bulletin for my model?
Rheem publishes technical service bulletins by product family on its website. The codes in this guide come from bulletin 1330, which covers the Generation 4 heat pump water heater.
Get a Rheem Alert Code Diagnosed
Read the code off the display before you call. It shortens the visit and it often decides which part comes on the truck.
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