What is an OBDII Drive Cycle Test?
An on-board Diagnostics II (OBD-II) drive cycle test refers to a functional set of steps that a driver must take in order for the vehicle to test itself for emissions related failures. They are called drive cycles because the vehicle must achieve several conditions in proper succession and for the proper duration. In other words, it must cycle through many different conditions required before it it will approve of the emissions related systems for the engine.
What are OBDII Drive Cycles?
OBD-II vehicles, mostly 1996 and newer, have strict emissions guidelines imposed by state and federal laws, so the manufacturers are required to add some self-testing features into vehicles for compliance with emissions testing equipment. This self-testing protocol is basically a succession of steps beginning with things like cooling the vehicle, starting the vehicle, warming the engine, driving a particular speed for a set duration or distance, slowing, idling, etc. Once all of these conditions are met, the vehicle will understand whether the emissions related components are functioning properly, or if there is a failure somewhere in the system.
What symptoms require an OBDII Drive Cycle Test?
After a repair which illuminated the check engine light is complete, if a drive cycle needs to be completed to verify the repair, the check engine light will stay on, and the OBD-II trouble codes stored or pending will remain until the drive cycle is complete. Aside from this, when it comes time for emissions testing, the vehicle will not pass dude to monitors which are not ready for testing. This means the vehicle has not yet tested itself, so it cannot report this information to the testing equipment at the emissions testing facility. The real symptom here would be failure of an emissions test, or the check engine light will not turn off after a repair.
Can I drive when monitors are not set?