At my wits end here ... Last month, I replaced the Right-Front CV Axle assembly and the front hub/bearing assembly. About a week later, the ABS light went on, the orange triangle with an exclamation point went on, and I got a message about the ABS Anti-Skid system. I don't have the car with me so don't have the exact message at the time of writing this ... I got occasional pulsating/grabbing at low speeds on that wheel, especially when coming to a stop. Sometimes the AWD light would go on when turning hard. I pulled the wheel off and saw that the hub bolt came completely out, only being held in place by the little plastic cap... Either I did not torque down the axle/hub bolt correctly, or forgot to tighten it at all. I tightened it back down down with some thread locker to 35 ft/lbs or so(?), pulled the ABS sensor and wiped a little grease off of it.

After assembly, the ABS light went off and everything was fine for about a week, and perhaps 400 miles. Then the exact same symptoms came up. I double checked the hub/axle bolt and it was still tight. I tightened it a little more, cleaned the sensor, blew off everything even remotely in or around the hub assembly with an air compressor even spraying brake cleaner into the sensor hole while rotating the hub. I cleaned it out as well as I could.

I assembled it and the problem went away for another week, then the same symptoms again. Today, I got a new bolt directly from Volvo (30640878), added extra thread locker and torqued it to spec, 35Nm (~26ft/lbs) plus 90 degrees. I did not remove the wheel or check the sensor. This made the issue go away for about fifteen minutes and then it came right back.

Any ideas? My thought is that the issue must be down at the wheel somewhere, because cleaning the sensor makes it hunky-dory for a week or so. Maybe a large hammer?