It's an easy job if you can get the old sensor out
.
First off you need to slacken off the wheel nuts before you jack the puma up. When the wheel have been losen off you need to jack up the front and place some axle stands at a suitable place. Once your puma is in the air and supported by the stand un do the wheel nuts all the way and remove the wheel.
If your puma has front arch carpets, your next job is to remove it. On the FRP there is 4 or 5 torx bolts which need to be removed and I assume it will be similar for the regular puma.
Once you have removed the carpet you should see a White connector which is close to the suspension strut but is screwed to the chassis. This is where the sensor joins the loom and needs to be disconnected.
When you have disconnected the conecter follow the sensor round to the knuckle, you will find it is clipped in place near the tie rods. Remove it from the clip.
Now if I was you I would remove the brake disc and caliper to make more room for myself but you may be able to do it with the brake disc and caliper in place. You need to remove an 8mm bolt which bolts though the sensor into the knuckle.
Once you have the bolt out, in comes the hard bit trying to get the old sensor out. In theory it should just pull out and if it does you should of know removed the old sensor and ready to put the new sensor in.
If the sensor dosnt come out drown it in WD 40 for a few hours and re try.
Now on putting the new sensor in, firstly have the new sensor and bolt ready. Then you need to clean the hole where the sensor fits though a little. Just to remove some of the rust to make sliding in the new sensor easy.
Once you has cleaned the aera work the opposite way to how you took the old sensor out. Always use a new bolt and tighten to 8NM.