A driver determines the trouble code on a PT Cruiser by using an On-Board Diagnostics Two Scanning Tool, or taking the car to a mechanic that has the tool. Information on these codes is available on OBD-Codes.com, as of 2015.
On-Board Diagnostics Two is the diagnostic standard used on all vehicles beginning in 1996. When the diagnostic detects an issue, it creates a trouble code related to the issue, and illuminates the vehicle's Check Engine light to alert the driver.
An alternative method for obtaining the trouble code is turning the key several times in quick succession. The driver must put the key in the ignition and turn it from the off position to the run position three times. He does this by turning the key back to off each time after putting it in run. The third time, he leaves it in the run position. He must do all three turns within five seconds.
When done correctly, the vehicle displays the trouble code on the odometer. If there is no trouble code, it displays the word "done." If the driver has trouble with this method, he should verify that he's turning the key to the run position, which is right before the start position. He must see the odometer illuminate each time he puts the car in the run position, before turning it off.