incorrect wheel bearing Installation????

Had my mechanic replace the 2 front wheel bearings last week on CLS500. I also replace the front rotors and pads myself. when I took the car for test drive ABS and ESP warning lights turn on.  Check codes with Icarsoft I980 and got code for front Left sensor.  I replace it and I'm still getting same warnings. Check it again and got same code left wheel sensor. Went and got another sensor and replace it for a 2nd time and I'm still getting same warning lights and same code.   Could the mechanic have installed wheel bearing incorrectly?? Could the coded ring that the sensor reads be installed backwards??