Instructions To Replace Front ABS Speed Sensor

[Nick1981-1]

Hi all, I thought I would share my experience and instruction on how to replace a front ABS Wheel Speed Sensor.

Symptoms: ABS light illuminated
Buzzing noise from rear of car and ABS activation at low speed

Make sure it is your sensor that is causing the problems. Get your codes read.

Firstly, disconnect the battery using the proper disconnection method.

1.) Loosen wheel lug nuts and jack up the car and support on axle stands

2.) Undo wheel nuts and remove wheel

3.) Using a small flat end screwdriver remove the small round plastic fixings that hold the wheel arch liner in place

4.) Remove 2 torx screws on the wheel arch liner at the bottom, one is underneath on the sill. Remove the wheel arch liner completely

5.) Unscrew the torx screw that holds the ABS sensor to the hub assembly, use some penertating oil if seized on

6.) Try to remove the sensor from the housing, if you are lucky it will just pull out, I was not lucky and snapped the thing off trying to remove it. If it snaps off you will need to drill the rest of the sensor out of the housing. Took about ten minutes to do. Start off with a small drill bit then increase size as you go. Be very careful not to damage the reluctor ring which is directly behind where you are drilling. Remove old sensor

7.) Using wd40 or penetrating oil, carb cleaner etc wire brush the sensor housing, both inside and out not forgetting the flat surface where the sensor sits on. This is imperative that it is clean as rust and dirt can cause the sensor to sit at the wrong distance from the reluctor ring and cause further problems.
Do the same with the reluctor ring, wire brush, wd40 and clean it. Also check the ring for any damage, chips in the teeth or corrosion. If the ring in corroded or damaged, this will need to be replaced

8.) You will see a rubber gromit that the sensor wire passes through into the engine bay. Pull this gromit out and pass the sensor through and into the engine bay

9.) Look for the blue plastic plug that connects the sensor. In my case I was changing the drivers side one which was really fiddly to find. It is under the air intake housing in a little crevice. If you shine a torch in this area you will see it. To give myslef more room I removed the coolant expansion tank which opened up a lot more space to get at the plug. To do this undo the bolt on the right hand side of the tank then undo the small hose using a pair of needle nose pliers. The expansion tank will now move to one side out of the way. Try not to spill too much water

10.) Give the sensor wire a little tug and the plug will come loose from its bracket holding it onto the inside of the engine bay

11.) Using a flat blade screwdriver prise the metal retaining clip from the top of the plug

12.) Unplug the old sensor and disgard

13.) Feed the new sensor through the rubber gromit intowards the engine bay and plug the new sensor into the plug

14.) Replace the metal retaining clip on the plug

15.) Install the sensor into the housing on the back of the hub assembly. It is a very tight fit so I used an old rag to protect the sensor and very gently tapped the sensor into place. Make sure the sensor is perfectly lined up

16.) Replace the sensor torx screw

17.) Clip the sensor wire onto the retaining bracket on the side wall of the wheel arch ensuring enough wire for wheel turning and movement

18.) Secure the rubber gromit where the wires enter the engine bay

19.) Re-install the wheel arch liner

20.) Re-install the wheel

21.) Tighten wheel lug nuts

22.) Remove axle stands and jack

23.) Torque wheel nuts

24.) Re-install the coolant expansion tank ensuring the hose is properly secure and tight

25.) Top up coolant dependant on how much you lost removing the pipe


Job done


Test drive, light went off 15 metres down the road and no more problems.

Hope this helps anyone suffering ABS sensor problems

Thanks

Nick

[Capncol]

Good write up. Thanks

[tenpole]

Nice one.

[frogmanbrabs]

I tied some string to the old sensor so that I could re-attach it to the new sensor to make pulling it through from the engine bay easier. Is the screw holding the sensor in place on the hub a special screw, because I think the previous owner has just put something with the correct thread in place to hold the sensor. It doesn't seem like it's the right one for the job.