1, check the pressure switch: use a multimeter to measure the conduction state of the pressure switch. Usually, the pressure switch consists of two groups of wires, and each group of wires should be conductive. If any group of wires are found to be non-conductive, this indicates that there is a problem with the pressure switch.
2. Clean or replace the pressure switch: If the contact of the pressure switch is poor, you can use fine sandpaper to gently polish the contact to improve its contact. If the pressure switch is damaged, it needs to be replaced with a new one.