Whirlpool Washer LF Error is a water fill error, it stands for Long Fill. It means that the main control has not gotten a signal back from the water pressure sensor which means that water is not filling the tub or not filling the tub fast enough. The control will shut down the cycle and report the LF error.
In most cases the LF (Long Fill) Error is caused by either low water pressure, stopped up screens on either the water supply lines or the water inlet valve. If the screens are clean and not causing any kind of blockage then the water inlet valve needs to be replaced. In some cases this can be caused by a bad main control but the causes above are much more common.
The replacement valve for the Whirlpool washer models WTW7500 can be ordered from the link below:
This Whirlpool Washer LF error troubleshooting and repair information applies to model WTW7500GC and all the models listed under the related models section below.