Hi! I am new to the boards and posted an electrical question on the mechanical board but I believe this board is where I should have posted. The previous owner of the home I just purchased pulled power off my washer outlet to power a bathroom light and outlet. The washer outlet is a 20A circuit run with 12Ga wire. Power to the bathroom is run with 14Ga. Do I need to replace the undersized wire due to a possible overheating problem? Thanks.

yes. this must be an older home. new codes require bath receptacles (all must be on Gfci devices) to be run in 12 wire and the lighting should be on another circuit can be 14 and on a 15 amp breaker. The bath should not be on with the washer circuit. if you operate a hair dryer and the washer at the same time, you will overload the circuit and trip the breaker.