The PT Cruiser's computer sends a code to a light on the dash when one or more of the engine's sensors malfunctions. If the light comes on and stays on, that is a hard code. If the light comes on, but goes out during driving, or the next time you start the car, that is a soft code. The problem sensor or the component that is causing the computer to send a soft code -- such as bad plugs or wires -- must be repaired before you can reset the codes, or else the code will just come back.
Plug the code scanner into the data port, which is under the dash and just to the left of the steering column.2
Turn the ignition key to the "On" position, but do not start the PT Cruiser.3
Press the "Erase" key on the code scanner, and the scanner will erase the codes.