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

Bradford White Ultra Low NOx D series gas error code 63 flashes

Pilot flame extinguished, unit auto resets

Needs attention soon

Also written as six-three, 6-3, six three flashes

Quick answer

On Bradford White Ultra Low NOx D series gas, 63 flashes is a fault. It means pilot flame extinguished, unit auto resets. A first thing to check: Unstable pilot.

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: Needs attention soon
First safe check: Check the vent length against the manual limit, since a short vent is a common cause of an unstable pilot.

Checked 2026-09-26

What 63 flashes means on this model

The pilot was lit and went out on its own, so the control reset. It shares its root causes with a pilot that will not light, and adds two more that only show up once the pilot is running: not enough combustion air, or gas pressure below what the pilot needs to hold.

Symptoms you will notice

Six-three flashes, then a three second pause
Pilot goes out on its own after running normally
Unit relights, holds for a while, then drops out again
Problem is worse in windy or drafty conditions
Pilot looks correct right up until it extinguishes

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:

Unstable pilot
Pilot tubing kinked or blocked
Oxidation build up on the pilot electrode
Wire damage to the pilot assembly or a poor connection at the gas control
Insufficient combustion air
Insufficient gas pressure

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.

Check the vent length against the manual limit, since a short vent is a common cause of an unstable pilot.
Check gas pressure at the appliance, particularly if the problem is worse when other gas appliances in the house are running.
Look for a strong nearby draft, such as a leaking cold air return, a backdraft, or a laundry exhaust fan running.
With the power off, check the pilot wiring for a break where it passes through the jacket.

Do not do these

×Do not prop the pilot open to keep the burner available. You lose the supervision that shuts the gas when the flame goes out.
×Do not ignore a pilot that will not stay lit. Each drop is a cold start, and repeated cold starts crack the combustion chamber.
×Do not attempt to increase gas pressure to stabilise the pilot. Low pilot holding pressure is usually a supply or regulator problem that has to be found.

When to call a technician

Book a technician, do not keep resetting it

This fault will not clear on its own. Every power cycle gives the control one more failed attempt, and repeated attempts are what turn a cheap part replacement into a seized or contaminated system.

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.

Observing the pilot and checking vent length are reasonable for a homeowner. Gas pressure measurement and pilot assembly work are licensed technician jobs.

What it costs to fix

Parts

Pilot assembly $60 to $180. Thermocouple $25 to $70. Gas pressure regulator $40 to $120.

Labor

One to two hours for pilot service. Add time if gas pressure has to be investigated with a manometer.

DIY or technician