What is OBDII?

OBDII (On Board Diagnostics-Second Generation), is a computerized system on newer model year vehicles (1996 and newer) that monitors systems for proper functionality. The OBDII utilizes an on board computer to test and monitor all the computerized components and systems of the vehicle.

How are malfunctions detected?

OBDII testing uses a scan tool that plugs into the vehicle's computer and determines that the emission system and components are working properly. The test downloads stored information from the vehicle's computer to identify emission systems or components that are not working properly. When an emissions control malfunction is detected, a dashboard light illuminates stating "Check Engine" or "Service Engine Soon." If the OBDII system detects a problem, a corresponding diagnostic trouble code (DTC) is stored in the computer's memory. Using an OBDII scan tool, a repair technician can quickly retrieve diagnostic codes from the vehicle computer and make necessary repairs before a more serious problem develops.

Reasons why a vehicle may fail the OBDII test:

• Catalytic Converter failure
• Faulty gas cap
• Fuel metering out of specification
• Incorrect ignition timing
• Inoperative injection system and/or thermostatic air cleaner
• Wrongly routed vacuum lines
• Faulty Positive Crankcase Ventilation (PCV) System
• Faulty Exhaust Gas Re-circulation (EGR) System