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Error code reference

Bradford White Water Heater Error Code 6-4 flash

Undesired/false pilot flame sensed out of sequence; pilot valve stuck in open position

Bradford White codesBradford White water heater codes

Undesired/false pilot flame sensed out of sequence; pilot valve stuck in open position. System auto resets.

First step from the service manual

Replace gas control (page 19).

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What 6-4 flash means on a Bradford White water heater

The 6-4 flash error code on a Bradford White water heater indicates that the control system has detected a pilot flame signal at a time when no flame should be present. This is described as an undesired or false pilot flame sensed out of sequence, meaning the flame sensor is reading voltage or current through the thermocouple or thermopile circuit even though the pilot valve has not been commanded to open. The root cause is typically a pilot valve that is mechanically stuck in the open position, allowing gas to flow and sustain a pilot flame without any signal from the control board authorizing it.

The gas control valve assembly contains internal solenoid-operated valves that control both the pilot and main burner gas flow. When the pilot valve solenoid sticks open, either due to debris in the valve seat, a worn or failed solenoid, or internal corrosion, gas continues to pass through to the pilot even during idle or shutdown states. The control board monitors the flame sensing circuit continuously and flags this out-of-sequence flame detection as a fault condition. The system is designed to auto-reset, meaning it will attempt to clear the condition and resume normal operation without requiring a manual power cycle.

Because the fault originates inside the gas control valve assembly and not in external wiring or sensors, the recommended first diagnostic step is direct replacement of the gas control unit. There is no field-serviceable repair for a stuck internal pilot valve solenoid. Attempting to operate the heater with a stuck-open pilot valve represents a gas control anomaly that should be addressed promptly.

Source: manufacturer service documentation.

Common causes of 6-4 flash

  1. 01

    Stuck-open pilot valve solenoid

    Part replacement

    The solenoid inside the gas control valve that operates the pilot gas supply has failed in the open position, allowing continuous gas flow to the pilot burner. This is the primary cause identified for this fault code and requires gas control replacement.

  2. 02

    Debris or contamination in the pilot valve seat

    Part replacement

    Sediment, scale, or debris from the gas supply can lodge in the pilot valve seat, preventing it from closing fully. This mechanically holds the valve open and produces the same out-of-sequence flame signal.

  3. 03

    Failed or degraded gas control valve assembly

    Part replacement

    General internal wear or corrosion of the gas control valve can cause multiple internal components to malfunction, including the pilot valve mechanism. A faulty control assembly will not regulate gas flow correctly and must be replaced as a unit.

  4. 04

    Flame sensor circuit fault causing false signal

    Wiring / connection

    Although less common, a short or leak in the thermocouple or thermopile wiring circuit could produce a false flame-present reading at the control board. Inspect the sensor wiring for damage, corrosion, or contact with grounded metal surfaces.

See the test procedure for each cause

Frequently asked questions about 6-4 flash

What does 6-4 flash mean on a Bradford White water heater?
The 6-4 flash code means the control system detected a pilot flame signal when no flame was supposed to be present, indicating the pilot valve is stuck open. The system identifies this as an out-of-sequence flame condition and logs it as a fault. Bradford White water heaters with this code will attempt an automatic reset, but the gas control valve typically needs to be replaced to resolve the root cause.
Can I fix the 6-4 flash error myself on a Bradford White water heater?
The fix for this error code is replacement of the gas control valve assembly, which involves disconnecting gas lines and working directly with gas supply components. While a knowledgeable DIYer may be capable of this repair, it is generally recommended that a licensed plumber or gas appliance technician perform the work to ensure safe installation and proper leak testing.
Is the 6-4 flash error on my Bradford White water heater a safety concern?
A stuck-open pilot valve means gas is flowing to the pilot burner without authorization from the control board, which is an abnormal operating condition. While the heater's auto-reset function will attempt to manage the situation, a pilot valve that cannot close on command is a gas control failure that should be addressed promptly. Do not ignore this fault code or attempt to bypass the control system.
Will resetting the water heater clear the 6-4 flash code?
The Bradford White system is designed to auto-reset after detecting this fault, so the heater may resume operation temporarily on its own. However, resetting does not repair the stuck pilot valve that causes the error. The fault is likely to return and the gas control valve will need to be replaced to permanently resolve the condition.
How much does it cost to fix a Bradford White water heater showing a 6-4 flash code?
The repair requires replacing the gas control valve assembly, and total costs including parts and labor typically range from around $200 to $500 depending on the specific model, part availability, and local labor rates. If the water heater is older or still under warranty, it is worth checking warranty coverage on the gas control valve before purchasing a replacement.

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