P0500, speed sensor issue, weird case.
 

It is super weird for my car. It threw P0500 code a month ago and I still can't figure out what's wrong.

Basically, it shows CEL + ABS light + tracking light. I checked all 4 sensors and visually good. I asked a shop to scan everything and they told me something wrong with rear right sensor. I bought a used sensor from eBay and no luck. They checked again and said it was bearing issue. After replacing bearing it was good for a while but issue came back again (Car in shop, it was what I heard when they replace the bearing).

It's weird because within these weeks (before the shop did the bearing), the issue disappeared itself sometimes as I started the car, but came back while driving. But in most case, the 3 lights was on when starting the car. The issue even disappeared for a whole week but back after 100 miles driving.

What possibly could happen? I didn't do anything except installing a header and racing seats and OFT tune.

Any experts?

If a shop replaced a part without testing to see if the part is bad, you need to go a different shop. I'd also complain and get your money back, you didn't go there to replace a sensor, you went to fix a problem which they didn't do.

A lot of shops have some good parts put-er on-ers but shitty diagnostic techs. Just throwing parts at a problem is expensive and ineffective. They should have put that sensor on an scope to test the output and see if it is really bad. Instead they read a code and guessed.

I suspect that someone removed the half shaft without first removing the sensor. This bends the encoder scale and destroys the sensor. People have successfully straightened the scales but perhaps not yours.

Pull the sensor and while looking in there with a flashlight, rotate the axle. Is the scale bent?

They are not charging me anything for now. But I don’t know if they will charge me, they also mentioned something like diagnosis fee, which I am not really positive about.

Well, that makes sense- they need to be paid for their time. But if they charge you for just guessing, that's different