help problem abs friends

There is a 2004 model peugeot 307 premium, I changed the front wheel balls between the friends, I bought the original ball with the abs reader, but at first it was nothing, then he wrote an abs fault and now the abs does not come into play help me what should I do ...

Most likely the ABS sensor is defective or the cable is broken. My car has changed right at the end of April, this week it is on the left. It is still unclear what happened without having it connected to the computer.

friend with another idea

Does anyone hear my voice

This week I wrote that the left rear failed, there are sockets of the abs sensors under the back seat. I removed, sprayed the contact spray and put it back. Yesterday has not made a mistake today. Of course, I deleted the error with pp2000.