Quote:
Originally Posted by MetroMPG
Can you explain why it came on?
I think it comes from comparing the upstream O2 sensor against the post-cat sensor, no?
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Well, when the cat is cold, it's indeed not converting efficiently, and the cat was probably pretty cold from all the engine-off coasting. Probably comes from comparing the O2 sensors, not totally sure how it works. These newer cars have much cleverer ECUs and will pick up on this kind of stuff.
The way I see it, I'm saving a lot of fuel? lol