F4 Heating error. Haier HW70-BP14636N An F4 error code in a washing machine typically indicates a heating error, meaning the machine isn't able to heat the water to the correct temperature. This could be due to issues with the heating element, thermostat, or even the main control board. Other potential causes include a faulty water level sensor or a communication error. The most common culprit is a faulty heating element, which may be unable to heat the water. In our case, the problem is with th