The Chrysler PT Cruiser began production in 2001 and ended in 2010. Getting a service light on the instrument cluster on the PT Cruiser is indicative of having a diagnostic trouble code (DTC) or codes. Sensors and circuits send communication signals to the on-board computer. The computer trips the light when one or more of the sensors or circuits indicate there is a problem in the body, the chassis, or the power train. The DTC(s) should be diagnosed (and dealt with if necessary) before resetting the light. Most modern pocket scanners used to read and reset the codes are inexpensive.
Open the driver's door of the PT Cruiser and kneel down to locate the 16-point data link connector (DLC) under the dash. It sits up under the dash to the left of the brake pedal on earlier model Cruisers. Later models moved the connector slightly to the right, closer to the steering wheel column, but still under the dash.
Plug the pocket scanner plug into the DLC. Because of its unique shape, there is only one way to plug any connectors onto the DLC, making it foolproof.
Place the key into the ignition and turn it two clicks forward to the "II" position. This position provides accessory power and illuminates the instrument cluster without the engine running. It also provides accessory power to the pocket scanner.
Read the onscreen menu of the pocket scanner. The scanners are easy to use, but if necessary, read the manual provided with the scanner to navigate through the menu. Many modern pocket scanners are equipped with "Erase" buttons -- in that case, press erase to reset the code. Other models may have "Enter" or "Scroll" button(s) to navigate through a few different options (one of the options being the erase codes option).
Erase the code(s) with the scanner and start the engine of the Cruiser. Determine if the service light is out. If not, repeat the procedure. If the light is still on, it means there is a "hard code" that must be read (with the scanner under "Read Codes" option) and properly repaired.
Reading codes can be done using the scanner. The manual may provide a list of generic numerical OBD codes and some scanners will give a brief description of the code to assist in determining the fault. As mentioned in the introduction, simply clearing codes will not fix the problem. You can do it to see if something like a slight vacuum leak tripped the light, but if there is something more going on, resetting the light repeatedly can eventually cause more harm than good and damage other components.