Hi, Two weeks ago, I cleared the OBDII code(P0420) and then I drove 60 miles/per weekday(about 40 miles onhighway). Today, I check it again using OBDII reader, to my surprise, the catalyst monitor is blinking and indicating that its monitoring cycle is not done yet, is this normal? why take so long for cat monitoring process too finish? Thanks
It takes at least 2 driving cycles to reset the electronic control unit (ECU). There are specific parameters that define a driving cycle, such as sitting for X hours and having the coolant temp cool below Y degrees, then driving for Z miles with the coolant temp getting above A degrees, and the speed getting above C miles per hour for D minutes. The trick is letting the car sit long enough (overnight is usually long enough) and then driving it far enough and then repeating the pattern. A week is usually, but not always long enough.
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