Rheem gas water heater: what the status light means
If you smell gas
Stop: do not relight or troubleshoot anything. Rheem’s own words (first page of both Use & Care Manuals, AP23060 and the Low NOx AP23698):
- Do not try to light any appliance.
- Do not touch any electrical switch; do not use any phone in your building.
- Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s instructions.
- If you cannot reach your gas supplier, call the fire department.
- Do not return to your home until authorized by the gas supplier or fire department.
Calling from a neighbor’s phone means leaving the building first.
Rheem’s atmospheric (standard-vent) gas tank water heaters with a diagnostic gas control show one status light on the front of the combination gas control, next to the temperature knob. Rheem’s Use & Care manual for its FVIR residential gas heaters gives a status light chart: one blue blink every three seconds is normal, and red blinks — 2, 4, 5, 7 or 8 per cycle, plus 9 and 10 on the Low NOx models — are faults. The label on the control itself says: if the status light blinks red more than one flash every three seconds, see the Use & Care manual.
The status light is on the combination gas control (thermostat), the box on the front of the tank near the bottom with the temperature knob and the spark (igniter) button below it. Rheem’s label notes that when the knob is turned to OFF with the pilot lit, the light stays lit briefly and turns from blue to red. The model and serial number are on the rating plate on the tank.
Status light off
The combination gas control is turned off, or the pilot is not lit, so there is no millivolt power from the thermopile to light the status light.
A fault or shutdown: see the page for the owner steps and when to call for service.
Status light on steady
The pilot was recently put out and the thermopile is cooling down, or the temperature knob was recently turned to OFF.
Normal operation.
2 red blinks every 3 seconds
Low thermopile voltage, although the pilot is lit.
A fault or shutdown: see the page for the owner steps and when to call for service.
4 red blinks every 3 seconds
The high water temperature limit has tripped: the water got hotter than the control’s safety limit, and the heater has shut down.
A fault or shutdown: see the page for the owner steps and when to call for service.
5 red blinks every 3 seconds
Water temperature sensor failure.
A fault or shutdown: see the page for the owner steps and when to call for service.
7 red blinks every 3 seconds
The combination gas control (thermostat) has failed.
A fault or shutdown: see the page for the owner steps and when to call for service.
8 red blinks every 3 seconds
Flame sense error.
A fault or shutdown: see the page for the owner steps and when to call for service.
9 red blinks every 3 seconds (Low NOx models)
Chamber sensor failure: the sensor that watches the combustion chamber has failed.
A fault or shutdown: see the page for the owner steps and when to call for service.
10 red blinks every 3 seconds (Low NOx models)
Chamber temperature shutdown: the combustion chamber got too hot and the heater shut down.
A fault or shutdown: see the page for the owner steps and when to call for service.
Rheem’s manual: “CAUTION: For your safety DO NOT attempt repair of gas piping, Combination Gas Control (Thermostat), burners, vent connectors or other safety devices. Refer repairs to qualified service personnel.” For service it says to contact your installer, plumbing contractor or previously agreed upon service agency first, then Rheem’s national service department on 1-800-432-8373 with the model and serial number from the rating plate.
Sources
Rheem’s own manuals and pages only, read on the date shown. Nothing here comes from forums or third-party “codes explained” sites.
- Rheem Manufacturing Company: Use & Care Manual with Installation Instructions — Water Heaters, Residential Gas, FVIR Certified (AP23060 Rev 01), “Combination Gas Control, Status Light Troubleshooting” — Rheem residential atmospheric gas water heaters, 29 to 60 gallons, natural or LP gas — the manual linked from the Rheem Performance atmospheric XG40T06EC36U1 product page. www.rheem.com Checked 2026-09-29.
- Rheem Manufacturing Company: Use & Care Manual with Installation Instructions — Water Heaters, Residential Gas, Low NOx Emissions (AP23698), “Gas control (Thermostat), Status Light Troubleshooting” — Rheem residential Low NOx (10 ng/J, SCAQMD Rule 1121) atmospheric gas water heaters, 29 to 55 gallons. files.myrheem.com Checked 2026-09-29.