F430 wheel speed sensor

Replaced front pads recently and while bedding them in got and ABS failure light inevitably followed by CST warning as it is dependant. Tried resetting the battery to get rid of the code but it persisted. Took the car to Phil at DK Engineering who kindly read the codes on their SD3. Was the drivers side wheel speed sensor as I suspected and he reckons a complete coincidence re timing. Was probably about to go and the raised temps due to brake pad bedding pushed it over the edge.

It's a sealed unit, part of the hub bearing assembly so I'm going to have to remove the hub to check it out. I've already checked all the connections and they all look fine. Is there a way to test it on the car? Maybe using a multimeter? Anyone had this before and are they repairable or should I just order one off eBay now? Can get a used bearing and speed sensor assembly for £250 from Germany with 20k Kms on it.


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Thanks. No play in the wheel so current bearing is fine. Good news if you can change the sensor. I'll go ahead and order a used hub as it includes the sensor and just swap out the sensor. 250 for the lot is better than 1200 for a new one from Ferrari. Used parts have never worried me so ling as they can be verified. The other three corners are used so why pay a premium for a new one for this corner, imho of course. Thanks for the info. Im going to dismantle the current hub to confirm that the sensor can be swapped out.


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Cheers Voicey. You are absolutely right. I went on hearsay when in fact Eurospares have a new one for £362. I'm assuming the price I was told was for all four! OK - my plan is still to remove the hub this weekend and check what the damage is. The point regarding damage to the sensor ring often being caused by bearing failure is a good one and I'm going to check again for play before making any order. Thanks for the advice guys, I'll update with more info when I have it.

 

Good progress and problem sorted - thanks again guys. Existing hub/sensor was removed by disconnecting the sensor and accelerometer wiring as per the workshop manual. Stub axle backing plate is removed next, then the brake calliper - left the pads in and balanced it all just out the way. Then removed the rotor. The manual says to remove the stub axle from the car next but as I had both front wheels raised and so could turn the steering left and right, I found that I had enough access to reach behind and undo the four bolts that fix the hub carrier to the stub axle. A few light taps and the hub slid free. As you withdraw it you need to feed the sensor wire through the grommet at the rear of the stub axle and the complete assembly can be withdrawn.

As per the pictures you can see water had worked it's way in and corroded the hub and I assume this eventually worked it's way in to the sensor ring (the black ring at the top) and damaged the sensor. I have had the ABS/CST/Suspension warning lights on a few times before but a restart had always cleared them, so I'm guessing this happened over a few years. When I have time I plan to take it apart and see if a simple clean will sort it. It's a sealed unit though so I'm not sure if that can be done without damaging it so for now it has gone into the box of replaced parts. I cleaned up the stub axle surfaces, luckily no pitting as all the corrosion was on the hub carrier.

I ultimately went with a used hub supplied from Germany and off a 2007 F430 with 14k kms on it. My car has 19k miles on it. With postage it came in at just over £200 and arrived in two days - with complimentary pack of roasted peanuts! All looked very clean and the bearing ran smoothly. Fitted it on Sunday and torqued up all bolts as per the WSM. Turned the battery master switch back on and although the warnings were still there I wasn't too concerned as I figured I would need to run the car to clear the codes. Sure enough, 20 yards out the driveway and the ABS and CST codes cleared. Suspension warning stayed on. After running through the ECU reset procedure I switched off, waited a minute then restarted. All clear - very happy to see the clock back in the display!

Celebrated by hooning around a few country roads. Cheers all.
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Thanks. Out of interest have you seen a lot of them? I ask because I'm wondering if I should open and check/service the others - I'm tempted to do so as it's a relatively easy job. Also, would you recommend applying any high temp grease to the surfaces to help repel any moisture? I didn't do it this time but am now thinking that maybe I should. I'd need to be careful not to have any contaminate the sensor - what's been your experience with these?

 

Hmm - I'll let this one go but don't you be calling my Ferrari dirty and corroded Suspension components, like exhausts, tend to get dirty inside if you use the car. I'll hazard mine is one of the most well looked after you'll find anywhere.

 

So the sensor 'cap' can be gently prized off the top of the hub. Once off it revealed a good layer of dirt built up between the sensor in the cap and the sensor ring on the hub. There is a hole either side of the cap that I suspect allowed bits of the corrosion to enter the cap and ultimately prevent the sensor from detecting the ring below. I cleaned it all up with a combination of a small wire brush and electrical contact spray and then tapped it back together. No real pitting detected - just a long term build up of surface contaminants really.

I then connected it to the harness on the car and it didn't immediately throw an error but that's hardly a test. I'm going to test it out when I service the other three hubs, if it works I doubt I'll use it but it's given me a good insight into what preventative maintenance can be done on the hub and sensor - clean up any surface corrosion and blow out any dirt in the sensor caps with my airgun. Now that I have seen the construction I can see how they may fail. I'm not sure why the holes in the cap are there - perhaps for fitting or cooling but that certainly seems to be where the dirt entered.

If I feel the need I may even polish the stub axles
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Hi artic. Yup, that was exactly what I had. I needed to take the car to someone that had an SD3 to find out which sensor was faulty but removal and cleanup was pretty easy after that. I could have saved myself the cost of a replacement as I have since check the original and it works perfectly. I had already fitted the replacement by the time I realised how easy it was to clean up though. So now I have a spare sensor in my parts bin. By the way the code cleared after driving the car for about 50 yards after putting it all back together.

Edit: Just to add that the top of the sensor pops off like a cake tin lid. Just lift it gently with a flat head screwdriver.


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