5 Flashes on a Water Heater: What It Means

The Short Answer: Five flashes is a gas-control status code, and its meaning depends on which control your heater has. On Bradford White ICON atmospheric and A. O. Smith standing-pilot heaters it means a sensor fault. On Bradford White ICON power-vent, Rheem PowerVent, and A. O. Smith Ultra Low NOx models it means flame was sensed when there should be none. Both need a technician.

Find out which control is flashing

Status lights that count flashes are almost always on the gas control of a gas tank heater: the box where the temperature knob is, or a display on a power-vent unit. Before you look up any meaning, note three things:

• The brand and full model number on the rating plate.
• Whether the heater has a vent fan on top (power vent or fan assisted) or a plain metal draft hood (atmospheric).
• The exact pattern: five flashes followed by a pause of about three seconds, repeating. A fast “strobe” or a single flash every few seconds is a different status.

Most controls also have a label on the heater or inside the door that lists their flash codes. If that label is there, it is the reference for your heater.

Documented meanings of five flashes

Other brands and older control versions use their own tables. Some Bradford White direct-vent service literature, for example, lists five flashes as an “electronics, sensor, or gas valve fault” on certain controls. If your heater is not in the table, read the label on the control or look up the manual for your model number before acting on any meaning.

What each meaning involves

Temperature sensor fault. The control cannot read the water temperature, so it will not fire the burner. The sensor is a probe that sits in the tank, connected to the control by a wire. The fault can come from a damaged wire, a loose connection, or a sensor reading out of range. On Bradford White ICON atmospheric units, the parts involved are the temperature probe and, if the fault stays, the gas control. On A. O. Smith standing-pilot models, A. O. Smith’s handbook calls for replacing the gas control. Either way, you get no hot water, but nothing unsafe is happening.

False flame or flame out of sequence. The control sees a flame signal when it has not opened the gas, or after it should have closed. That can be a flame sensor shorted to ground, or a pilot or gas valve that did not fully close. This one matters more: a valve that does not close properly is a gas-safety problem, not just a nuisance.

What you can do before the visit

• Write down or film the flash pattern and note when it started (after a power outage, after work on the heater, out of nowhere).
• On power-vent models, check that the heater is plugged in and the outlet or breaker is on. Turning power off and on once is reasonable after an outage. If five flashes comes back, leave it off.
• Check that the gas supply valve to the heater is on and that other gas appliances work.
• If the code is a sensor fault and you need hot water, there is no workaround. Wait for the repair; do not adjust anything inside the control or burner area.

What the technician will check

For a sensor fault, the technician inspects the probe wire and connector and measures the sensor against the manufacturer’s resistance-temperature chart. A sensor that reads out of range is replaced; if the sensor is good, the gas control is usually the part at fault.

For a false-flame code, the technician looks at the flame sensor and pilot assembly for a short to ground, and checks whether the pilot or main valve closes completely. Parts listed by the manufacturers include the pilot assembly and the gas valve. A control that keeps sensing flame with gas off is replaced, not reset.

Both repairs are part replacements. Five flashes alone is not a reason to replace the whole heater unless the tank is also old or leaking. Related codes on the same controls: status light blinking 3 times, blinking 6 times, and the gas valve electronic fault message. All the codes we cover are listed on the error code hub.

Frequently Asked Questions

Q: Is five flashes on an electric water heater the same code? A: No. Standard electric tank heaters usually have no flashing status light, and the ones that do (heat-pump and some smart models) show codes on a display with their own tables. The meanings above apply to the gas controls named in the table.

Q: Will resetting the control clear five flashes? A: Cycling power or relighting may clear the light for a while, but the cause stays. Bradford White and Rheem both point to part checks or replacement for this code, so a code that comes back after one reset needs a technician.

Q: My heater flashes five times but I still have some hot water. Is that possible? A: Yes, briefly. The control stops heating when it sets the code, so the tank keeps whatever hot water it had, and that runs out over the next few hours of use.