Rheem Water Heater Status Light: Blue and Red Blinks

By Ray Bennett · Updated 2 October 2026 · 4 min read · Checked against the maker’s manual

Rheem Water Heater Status Light: Blue and Red Blinks

Short answer

On a Rheem gas water heater, one blue blink every three seconds is normal. Two red blinks means the thermopile voltage is low, usually a loose connector or a tired thermopile, and red counts of 4, 5, 7, 8, 9 or 10 need a technician. No light means the control is off or the pilot is out, and the pilot has to be lit before any code shows.

The gas control on a Rheem water heater has a small status light, and it tells you whether the pilot is burning and whether anything is wrong. One slow blue blink is what you want to see. A red count is the control telling you what failed.

Everything on this page comes from Rheem’s own use and care manual AP23698 for its residential gas water heaters, and its status light chart for the gas control. Rheem calls the gas control the combination gas control, or the thermostat.

Before you start

What to carry: a torch and a pen, and the lighting label on the heater itself. Ten minutes.

Gas or electric? This is the gas control on a gas water heater, natural gas or propane.

Light the pilot first. Rheem says the pilot burner must be lit to see the status codes. If the light is off, the first job is lighting the pilot with the instructions on the heater.

Count every three seconds. Rheem’s codes are a number of blinks every three seconds, in blue for normal and red for a problem.

What Rheem says to leave alone. If you smell gas, stop. Rheem’s manual says do not try to light any appliance or touch any electrical switch, leave, and call the gas supplier from a neighbor’s phone.

The sealed burner chamber and the gas control are service work. Rheem says not to attempt repair of the gas piping, the gas control, the burners or other safety devices, and not to remove the burner access door unless a qualified technician does it.

What the light is telling you

One blue blink every three seconds is normal. Two red blinks is the one code with an owner check; the other red counts need a technician.

Check 1Free, two minutes

Read the light

Off. Rheem lists three causes: the gas control is turned off, the pilot is not lit, or the thermopile is not producing enough power. Turn the control on and light the pilot: how to light a water heater pilot.

On constantly. Rheem says the pilot has recently gone out and the thermopile is cooling down, or the knob was just turned to OFF. Relight the pilot.

1 blink every three seconds, blue. Normal operation: the knob is at the pilot position and the pilot is lit. Set the knob to the temperature you want.

2 red blinks. Low thermopile voltage, although the pilot is lit. The next section is yours to check.

4, 5, 7, 8, 9 or 10 red blinks. Rheem’s answer to each is to contact a qualified service technician.

Every code in Rheem’s chart

Blinks	Colour	What Rheem says it means	Rheem’s answer
0	None	Control off or pilot out	Turn it on, light the pilot
1	Blue	Normal operation	Set the temperature
2	Red	Thermopile voltage low	Connector, wires, pilot assembly
4	Red	High temperature shutdown, the high limit tripped	A technician
5	Red	Water temperature sensor failure	A technician
7	Red	Gas control or valve failure	A technician
8	Red	Flame sense error, a false pilot flame signal	A technician
9	Red	Chamber sensor failure	A technician
10	Red	Chamber temperature shutdown	A technician

Reading the code, and the two red blinks

Rheem's way to read the code: pilot lit first, then count. If the pilot will not stay lit, keep the knob pressed while you count.

Check 2

Work the owner checks

If the pilot will not stay lit. Rheem says to repeat the lighting instructions, but keep the knob pressed in until the pilot is lit and the status code can be read fully.

2 red blinks: the thermopile connector. Rheem’s first check is that the thermopile connector is properly connected to the gas control.

2 red blinks: the wires. Rheem says to check the thermopile wires for damage and replace them if needed.

2 red blinks: the pilot. Rheem says to inspect the pilot assembly. A weak or dirty pilot flame heats the thermopile less: why a pilot keeps going out.

Keep the air openings clear. Rheem’s manual says never to block the combustion air openings around the lower part of the heater’s jacket.

When it needs a technician

Check 3Parts to a new heater

Know when to stop

4, the high limit. The water got too hot and the control shut the heater down. Rheem sends it to a technician: what temperature a water heater should run at.

5 and 9. The water temperature sensor or the chamber sensor has failed.

7. The gas control or its valve has failed, which means a new control.

8. The control sees a pilot flame signal it should not.

10. A chamber temperature shutdown. The burner chamber is sealed, and Rheem says only a qualified technician should open it.

Questions people ask

Why is my Rheem water heater blinking red?

Count the blinks every three seconds. Two red blinks is low thermopile voltage, which Rheem says to check at the connector, the wires and the pilot. Other red counts need a technician.

What does one blue blink mean?

Normal operation. Rheem says the pilot is lit and the knob is at the pilot position, so set it to the temperature you want.

Why is the status light off?

Rheem says the control is off, the pilot is not lit, or the thermopile is not making enough power. Light the pilot with the instructions on the heater.

What does 4 red blinks mean on a Rheem water heater?

A high temperature shutdown: the high limit has tripped. Rheem says to contact a qualified service technician.

Why does the light stay on without blinking?

Rheem says the pilot recently went out and the thermopile is cooling down, or the knob was just turned to OFF. Relight the pilot.

Can I see the code if the pilot is out?

No. Rheem says the pilot must be lit before the status light shows a code.

Sources: Rheem use and care manual AP23698, residential gas water heaters, gas control (thermostat) status light troubleshooting