4 flashesBradford White · Ultra Low NOx D series gas · Water Heater

Bradford White Ultra Low NOx D series gas error code 4 flashes

Excessive tank temperature

Stop using it

Also written as four flashes, 04

Quick answer

On Bradford White Ultra Low NOx D series gas, 4 flashes is a fault. It means excessive tank temperature. A first thing to check: Temperature sensor out of calibration.

Applies to: Bradford White Ultra Low NOx D series gas; Bradford White Ultra Low NOx residential D series gas codes · Water Heater
Type of code: Fault; Urgency: Stop using it
First safe check: Run a hot tap and measure the temperature with a reliable thermometer before using water near the appliance again.

Checked 2026-09-26

What 4 flashes means on this model

The tank went above the temperature the control will accept and the burner was shut off. The control stopped it before the temperature and pressure relief valve had to, which is why the unit needs resetting rather than simply restarting.

Symptoms you will notice

Four flashes, then a three second pause, repeating
Water is dangerously hot at the tap
Water at the hot tap fluctuates cold then scalding
You can hear the burner running longer than it should for the water drawn
Unit needs resetting and will not stay reset

Common causes

The code tells you what the control detected, not which part failed. These are the causes we see most often, roughly in order of likelihood:

Temperature sensor out of calibration
Failed or faulty gas control
Thermostat on the tank set higher than it should be
A failed thermostat or a tank that is too small for the household demand
Dip tube broken so the sensor is reading steam or empty space

What you can safely check

These are homeowner-level checks. None of them need you to open a live electrical compartment or work on gas.

Run a hot tap and measure the temperature with a reliable thermometer before using water near the appliance again.
Confirm the thermostat on the side of the tank is set to a normal domestic temperature and has not been turned up.
Look at the temperature and pressure relief valve discharge pipe and confirm it is clear and routed safely.
Note whether the unit is undersized for the household, which shows up as a fault that returns after reset rather than a single event.

Do not do these

×Do not reset the control and keep using the appliance without measuring the water temperature, because the relief valve is the last thing standing between a hot tank and a scalding.
×Do not cap, block, or re-route the relief valve discharge.
×Do not raise the thermostat setting to compensate for slow recovery. That raises tank temperature and brings this code straight back.
×Do not run water at the appliance while the water is coming out unexpectedly hot.

When to call a technician

Stop using the appliance and call today

This one is a safety limit, not a nuisance. The control is shutting the unit down to prevent damage or a hazard, and it will keep doing that until the underlying cause is fixed. Running it anyway risks the expensive failure it was designed to prevent.

This is a fuel-burning appliance, so treat anything involving a burner, gas valve or flue as technician work. If you smell gas at any point, leave the property and call the gas utility from outside rather than continuing to diagnose.
If the appliance has stopped mid-cycle, is making a noise you have not heard before, or smells burnt, stop reading here and call. Those are symptoms of something the fault code does not describe well enough.

Measuring water temperature and reading the thermostat setting are homeowner tasks. Working on the control, the thermostat, or the relief valve is a licensed technician job.

What it costs to fix

Parts

Gas control $150 to $350. Thermostat $20 to $60. Temperature and pressure relief valve $20 to $50.

Labor

One to two hours to replace the control or the thermostat.

DIY or technician