In cases where the ignition cylinder is severely damaged or has a broken key inside, decoding the door lock becomes the preferred method. Using the Lishi tool on the door lock provides the original key code, allowing a new key to be cut for the door and trunk while the ignition is separately repaired.

A critical component is the calibrated measurement scale built directly onto the tool's body. As the internal lever manipulates the pins, an external pointer moves across this scale, providing a precise visual readout of each pin's depth position.

Gently insert the tool into the keyway without forcing it. The tool should slide in smoothly, with the tensioning fork engaging the lock's face and the reading blade aligned with the pins.