As was suggested, clean the resonance ring well with brake clean through the wheel speed sensor hole with the sensor out of course. One thing to note when servicing these cars is to always disconnect the neg battery post. If you dont, and you are spinning the wheel/tire, even with the car off, the ecu usually picks up a differential in speed between the speed sensor you are working on and the other 3 which are not moving and throws a code. The codes usually self clear after a few miles or start/run cycles. It's worth mentioning, because often suspension work or brake work is done without doing this, and as the parts get manipulated codes get thrown, more of a future FYI.

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)