Honeywell Water Heater Error Code 8 Flashes

Eight flashes on a Honeywell water heater gas control valve indicates a power off failure. This means the control system detected that gas flow or the pilot flame did not shut off correctly when the control knob was moved to the OFF position. It is a safety-related fault that requires immediate diagnosis and is typically resolved by replacing the gas control valve.

Yes, this fault should be taken seriously because it indicates the gas control valve may not be shutting off gas flow properly. A pilot flame that continues burning when the unit is set to OFF represents a control failure that could pose a safety risk. Do not continue operating the water heater without addressing the fault, and if you smell gas at any point, leave the area and contact your gas utility company immediately.

A simple reset will not permanently clear this error if the underlying fault still exists. The 10-minute cool-down period described in the diagnostic procedure is specifically intended to rule out residual thermopile heat as the cause before relighting. If the condition returns after the cool-down and relight, the error will continue to appear until the faulty gas control valve is replaced.

First, set the control knob to OFF and check whether the pilot flame is still burning. If the pilot remains lit, the gas control valve has failed to shut off gas flow and must be replaced. If the pilot is out, wait 10 full minutes for the thermopile to cool completely, then relight the unit. If the 8 Flashes code returns after that cool-down period, the gas control valve still needs to be replaced.

The repair typically requires replacing the gas control valve, which generally costs between $150 and $400 for the part alone depending on the specific model. Adding professional labor for installation can bring the total repair cost to a range of $250 to $600 or more. In some cases, if the water heater is older, replacement of the entire unit may be more cost-effective than replacing the gas valve.