I did something stupid today. At a light I started off in 3rd gear instead of 1st, of course that went almost nowhere and I grabbed 2nd since I was sort of moving and went on. Look down at the dash and my CEL is on. I tried to reset it with the battery disconnected but got nowhere. Turned the key three times to see a code P0136, O2 sensor. I'm wondering if my stumble at starting off in 3rd caused the code, and also wondering if this might clear itself after a few short drives, I remember reading that some codes could, but if anyone has any experience please share.