Unplug your refrigerator and locate the water supply shutoff valve in your kitchen. This valve is likely located under the sink. Turn the valve off to shut off the water supply.
Turn the pipe valve at the rear of the ice maker to the "Off" position.
Locate the area where the valve connects to the pipe. Unscrew the valve from the line by gripping it with the wrench and turning it counterclockwise.
Use a wire brush or rag to clean out the interior of the valve. Flush with water to remove any residual gunk or debris.
Reattach the valve using the wrench.