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Error code reference

Honeywell Water Heater Error Code 5 Flashes

Sensor failure.

Honeywell codesHoneywell water heater codes

Sensor failure.

First step from the service manual

Turn gas control valve/thermostat knob to OFF, turn main gas supply OFF, replace the gas control valve/thermostat.

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

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What 5 Flashes means on a Honeywell water heater

A 5-flash error code on a Honeywell water heater gas control valve indicates a sensor failure within the gas control valve assembly. The internal sensor referenced by this fault is embedded directly within the gas control valve itself and monitors critical operating parameters. Because the sensor is not a separately serviceable component, the fault points directly to the gas control valve and thermostat unit as the assembly requiring replacement.

The sensor failure typically manifests when the internal thermistor or sensing circuit within the gas valve loses calibration, sustains physical damage, or experiences an electrical fault that produces readings outside acceptable operating ranges. This can result from age-related component degradation, water heater overheating events, or internal electronic failures within the valve. Since the control circuitry and sensor are integrated into a single sealed unit, there is no way to repair or recalibrate the sensor independently.

The diagnostic procedure outlined for this fault is straightforward but requires complete shutdown before any work begins. The gas control valve knob must be turned to the OFF position, the main gas supply must be shut off at the shutoff valve, and then the entire gas control valve and thermostat assembly must be replaced. Attempting to operate the water heater while this fault is active is not recommended, as the sensor failure compromises the valve's ability to accurately regulate operation.

Source: manufacturer service documentation.

Common causes of 5 Flashes

  1. 01

    Failed internal gas valve sensor

    Part replacement

    The sensor is integrated directly into the gas control valve and thermostat assembly. When it fails due to age or electronic degradation, the entire valve must be replaced since the sensor is not separately serviceable.

  2. 02

    Overheating damage to the gas control valve

    Part replacement

    Excessive water heater operating temperatures can damage the internal electronics and sensing components within the gas valve. Signs include a history of high-temperature events or scorching near the valve body.

  3. 03

    Age-related component degradation

    Part replacement

    Gas control valves have a finite service life and the internal circuitry can degrade over time, causing sensor readings to drift outside acceptable limits and trigger this fault code.

  4. 04

    Internal electrical fault in the gas valve

    Part replacement

    A short circuit or open circuit within the sealed gas valve electronics can trigger a sensor failure code. This type of fault does not resolve on its own and requires valve replacement.

See the test procedure for each cause

Frequently asked questions about 5 Flashes

What does 5 Flashes mean on a Honeywell water_heater?
Five flashes on a Honeywell water heater gas control valve indicate a sensor failure within the gas control valve and thermostat assembly. The internal sensor is not a separate replaceable component, meaning the entire gas control valve must be replaced to clear this fault. The water heater should be shut down until the repair is completed.
Can I fix the 5-flash error on my Honeywell water heater myself?
The repair requires turning the gas control knob to OFF, shutting off the main gas supply, and replacing the gas control valve and thermostat assembly. While some experienced DIYers can complete this replacement, gas appliance work carries safety risks and local codes in some areas require a licensed professional. If you are unfamiliar with gas line connections, hiring a qualified technician is strongly recommended.
Is it safe to use my water heater when it shows 5 flashes?
No, operating the water heater with an active 5-flash sensor failure is not advisable. The sensor failure compromises the gas control valve's ability to accurately monitor and regulate heater operation. The unit should be shut down by turning the gas control knob to OFF and closing the main gas supply until the valve is replaced.
Will resetting my Honeywell water heater clear the 5-flash error code?
A simple reset will not clear the 5-flash sensor failure code because the fault is caused by a hardware failure inside the gas control valve, not a temporary condition. The code will return as long as the faulty valve remains installed. Replacement of the gas control valve and thermostat assembly is required to resolve the fault permanently.
How much does it cost to fix a 5-flash error on a Honeywell water heater?
The cost depends on the specific gas control valve model required and whether you hire a technician. Replacement gas control valves typically range from $100 to $350 for parts alone. Adding professional labor, total repair costs generally fall in the range of $200 to $600 depending on your location and the technician's rates.

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