CC hasn't worked for a couple of months. Tried onboard test with ignition switch but it said it was OK. Just replaced left front wheel bearing and front brake pads. Now the ABS lite is on, shop says it is a bad LF speed sensor causing both problems. They also said the sprocket, for the sensor, on the axle might be dirty. There is no pickup sprocket on this axle. I removed the sensor to remove knuckle when I replaced the wheel brg and wiped it off before installing. I will ohm sensor before replacing it. Any suggestions?