If the light went on 1,000 miles in, there's a chance you didn't get the sensor in the right place. First time I did it I realized just before it was too late, that I was putting the sensor too far forward in the pad. I doubt it would trip at 1,000 miles, but check that if you don't see bad connection or the like.
Also, there's a water tight gasket in the connection, and it's possible it got lost, water got in, and corroded things enough where you got a signal--not sure if that's electrically possible or not, but it's easy enough to look for.
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