1999 Audi A4 censor lights

my 1999 audi a4 has the brake,ABS and air bag lights in the odometer on at all times even tough im driving ...i was told by someone that the abs censor is by the front wheel and because the cv boot is ripped on both sides ,dirt is probably getting in to it and causing the censor to read that their is a problem.you think by replacing the cv boot and cleaning the censor might resolve the problem?
And about the air bag i dont really now what is going on