Having just replaced the rear suspension arms, I now have an "ABS System Faulty" warning which will not go away. I've tried numerous combinations of sensors and hubs (both original and new) , and rebooted the BSI several times, but the warning persists. I have 2 questions (more to follow!!!):
1. Is it possible that the fault is fixed but the warning needs to be removed by a code reader? And, if it does just need removing, what is the cheapest option to do so? In 15 years and 170,000 miles I have never had to connect a code reader or Lexia etc.
2. Do the ABS sensors actually need to be in place (ie adjacent to the magnetic ring in the hub) for the car to recognise them as serviceable or do they just need to be connected (ie under the rear seat above the fuel pump)?
Background. Knowing that the fragile, plastic ABS sensors were likely to get damaged during removal from the suspension arms, I bought 2 new after-market ones just in case.
RIGHT SIDE. I damaged the right sensor so cut its cable. I replaced the arm with a second hand one and fitted a new ABS sensor, but initially with the cable routed through the rear door. Initially, I got an ABS warning, but after extensive trial and error combinations of connectors and sensor it went away, so I believe the right side is good, with original hub and a new sensor. I finished the right side before beginning on the left.
The left sensor came out OK and remained connected to the car. I had to fit an after-market hub (see other thread about rotating stub-axle). I refitted the original sensor and got the warning. I replaced it with the new sensor (again fed through the rear door) - still got the warning. I fitted in turn the original sensor and a new sensor into a loose original hub and still got the warning. So, every combination of an old or new sensor fitted to an old or new hub gives the warning!! How frustrating!
The new (left) hub appears Ok and certainly the sensor ring is magnetic.
I have also made sure that in every case the air gap is correct, which prompts my 2nd question above.
When both ABS sensors are disconnected, a 2nd additional warning appears -"ESP system faulty". Hence, it is possible to confirm whether the left or right sensors are at fault. Hence, I remain sure it is the left side which is causing the warning.