Brandon D Coxs Creek , KY February 05, 2017 Appliance: Whirlpool Washer WFW9400SW02 Whirlpool Washer Wfw9400sw02: Washer F20 error code. How to replace Water Valve. Replaced Water Valve (WP8182862). Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes