Originally Posted by
Rob M
Old thread i realize, but two things to keep in mind when emissions checks are not ready. The oxygen sensor check may never complete if you do lots of short trips. With obd2 diagnostic tool connected, it took me a 13 mile highway trip to get a completed test. The evap check actually requires that you cycle through most of a tank of gas to complete. After a battery replacement it was not ready for well over 200 miles! But that was because i was only putting in a few gallons of fuel at a time and never filling the tank enough. you need to fill up to around 3/4 tank, and then drive to around 1/4 tank to complete that evap check.
A third thing to keep in mind, every vehicle manufacturer has a different way to validate an OBD 'drive cycle', depending on that vehicle, to reset them. Generalizations cover many individual circuit tests within the set drive cycles, but the manufacturers drive cycle will reset if nothing is out of tolerances (defective) within that vehicle. Best to get a hold of the drive cycle, or not. Eventually it'll reset after a few trips unless something isn't working right (out of tolerance).
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