On-Board Diagnostic Codes

OBD 2 is an on-board diagnostic system which allows one to access the vehicles computers to search for fault codes on a vehicle. This was a standardized system in 1996, but some vehicles may have been equipped with the OBD 2 system a couple years earlier. Prior to the OBD 2 system, other forms of on-board diagnostic systems were used but were vehicle specific instead. This modern system is intended to have some generic characteristics between all vehicle manufacturers so it is easier to troubleshoot any vehicle faults.

Vehicle manufacturers used a generic female 16 pin plug (pinout diagram found below), generic codes (code diagram found below and code means above), and a generalized location which was two feet away from the steering wheel. In order to scan these codes, various methods can be used which include a hand-held scan tool (tutorial found below), mobile WiFi devices, computer based scanning programs, and data loggers. Beyond scanning vehicle faults, on-board diagnostic ports are also used for emission testing vehicles, performance tuning, and vehicle telematics.

When there is a fault, it will not always trigger a check engine light right away. Sometimes it might be a minor error or something which is intermitting. As for what could be the possible culprit, it could be as simple as a loose fuel cap or perhaps a more complicated issue or as expensive as a plugged catalytic converter. Once that light a illuminated, the issue will need to be repaired in order to fix the error permanently. Once that error is fixed, it may take a little driving time for that check engine light to go out or it can be erases manually. Erasing the code manually can either be done my using a code reader or disconnecting the vehicle's battery for a certain amount of time.