5 years with the "3 amigos"

Hi all.
It's been suggested I should post this teaser here, having already had a couple of responses.
10 years with my P38 4.6 Vogue, and not all plain sailing as you can imagine.
I know there have been many posts on this subject but my experience does not, I belive, fit previously stated scenarios.
About5 years ago my local specialist replaced a worn front diff. He drilled out the ABS sensors on both hubs and replaced with OEM sensors. (£86 each??!!)
Since then, the old girl just chews through sensors. OEM to Ebay specials. Non last more than a couple of thousand miles.
My specialist has plugged in his very expensive computer but nothing shows. But replace the sensor(s), only the front, and the fault goes away.
An alternative ABS ecu has been fitted with no change. Exciter rings have all their teeth and are clean. Wiring has been checked for continuity from sensors to ecu.
My man has no explanation and is as frustrated as I am.
Just to sum up, ABS and Traction failure lights come on, accompanied by irritating beeping. Replace front ABS sensors, fault goes away.
What, if anything, can cause regular failing of these sensors?

My MY2000 has gone through 2 OSF sensors in 4 years.
Each time it is the sensor that fails. I replace with the cheapest sensors available and consider them a consumable.
Sensors should measure about 1k - 1.2K ohms at their plugs. If the sensor is Open circuit or <1KOhms it is duff.
Nanocom shows live voltages back from each sensor. 3 of mine are showing 2.3v and the new cheapo is showing 2.2v.
Looking upstream towards the ABS ECU I see 5.3V on each plug.
For me, replacing the sensor is always the answer, I would not waste £86 on them when they are such a simple device and take only 30 minutes to change out (unless corroded in).

To add.. the new sensor i put in measured 1.23K ohms, worked for a few days then threw an error.
Took it out, measured the same 1.23K. plugged it in without replacing and the error went away. Put the sensor back in the hub and the error returned!
Another new one and so far no further error

DanClarke said:

My MY2000 has gone through 2 OSF sensors in 4 years.
Each time it is the sensor that fails. I replace with the cheapest sensors available and consider them a consumable.
Sensors should measure about 1k - 1.2K ohms at their plugs. If the sensor is Open circuit or <1KOhms it is duff.
Nanocom shows live voltages back from each sensor. 3 of mine are showing 2.3v and the new cheapo is showing 2.2v.
Looking upstream towards the ABS ECU I see 5.3V on each plug.
For me, replacing the sensor is always the answer, I would not waste £86 on them when they are such a simple device and take only 30 minutes to change out (unless corroded in).

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Thanks Dan.
Pretty much the conclusion I have arrived at myself.
I am just perplexed by why they should fail like this. No moving parts or circuit boards/chips. Just a passive sensor. It's irritating!
Odd, also, that the original sensors were OK for 15 years, apparently, they were well rusted in which is why he drilled them out, but began failing after the diff replacement?
As you say, easy to swop out. If my man had disconnected the originals at the plugs instead of drilling them, maybe this issue would not have developed?

Are the wheel bearings OK on the front wheels? I've seen two later p38's around the 2000yr time with duff front diffs?
Has the height of the hub been adjusted to low and are there any leaks from the shaft seals?

Mark Piercy said:

Are the wheel bearings OK on the front wheels? I've seen two later p38's around the 2000yr time with duff front diffs?
Has the height of the hub been adjusted to low and are there any leaks from the shaft seals?

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That's a good call, I noticed my first failed sensor was greasy at the end, maybe after 21 years my seals are going.

DanClarke said:

That's a good call, I noticed my first failed sensor was greasy at the end, maybe after 21 years my seals are going.

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It's a sealed bearing unit Dan so probably needs changing.

Is the end of the failed sensor showing any signs of contact damage?

Datatek said:

Is the end of the failed sensor showing any signs of contact damage?

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^^^^What he said....

Mark Piercy said:

Are the wheel bearings OK on the front wheels? I've seen two later p38's around the 2000yr time with duff front diffs?
Has the height of the hub been adjusted to low and are there any leaks from the shaft seals?

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Hi Mark.
All I can say re wheel bearings is it keeps passing MOT and no noise up front or heat. OSF drive shaft replace a couple of years ago and no sign of oil leak at that time. Similarly, brake pads regularly serviced with no sign of oil leaks from axle.
I would hope my landy "expert" would have considered that last time he had it.
But, again, would fault clear for 2k miles with new sensors if it was bearings?
I have spent many a "happy" hour removing and refitting sensors checking the "air gap" (they come out really easy when you change/inspect them as much as I have!). Never seen any evidence of contact with exciter ring and generally follow RAVE to push them right in with a new bush each time.
The only thing I have noticed is that the raised collar on the hub, against which the Bush sits, has a bit broken off, possibly chipped off trying to remove original sensors, but it's only a small bit and the Bush seats OK against the remaining collar.

Mark Piercy said:

Are the wheel bearings OK on the front wheels? I've seen two later p38's around the 2000yr time with duff front diffs?
Has the height of the hub been adjusted to low and are there any leaks from the shaft seals?

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Just to add, damaged collar is on OS only.

Excessive vibration or heat ?

Patricia7 said:

Excessive vibration or heat ?

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Yes but it's the only excitement she gets.

Patricia7 said:

Excessive vibration or heat ?

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Hi Patricia,
No vibration through steering wheel and I regularly feel front wheel centres as sticking calipers have been a feature over the years, easily detected by hot wheel centres.
Another odd thing is it is always the front sensors that fail. As far as I am aware the rear sensors are the originals, 21 years old, and still going strong! I certainly haven't changed them in over 10 years of ownership!
So why oh why do the fronts keep failing!!??

PTMADRID said:

Hi Patricia,
No vibration through steering wheel and I regularly feel front wheel centres as sticking calipers have been a feature over the years, easily detected by hot wheel centres.
Another odd thing is it is always the front sensors that fail. As far as I am aware the rear sensors are the originals, 21 years old, and still going strong! I certainly haven't changed them in over 10 years of ownership!
So why oh why do the fronts keep failing!!??

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It's a puzzle. I would still suspect contact damage.

or poor replacement parts

Is the wire being cut ,or trapped due to not being rooted the right way to the hub or a faulty plug that would stop continuity, just a thought ......

dubbleRR said:

Is the wire being cut ,or trapped due to not being rooted the right way to the hub or a faulty plug that would stop continuity, just a thought ......

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Hi dubble,
Replacing one or other sensor roughly every 2k miles I have never come across a damaged wire. I do use the hub/wing mounted clips to position the cable to the plug which appear to make good contact and are secure. Sprayed with contact cleaner various times. All to no avail.
Datatej, I appreciate your comment but no evidence of contact on replaced sensors, that I can see anyway.
As I have nantioned before, these sensors are passive, no moving parts, so what is there to fail?

PTMADRID said:

Hi dubble,
Replacing one or other sensor roughly every 2k miles I have never come across a damaged wire. I do use the hub/wing mounted clips to position the cable to the plug which appear to make good contact and are secure. Sprayed with contact cleaner various times. All to no avail.
Datatej, I appreciate your comment but no evidence of contact on replaced sensors, that I can see anyway.
As I have nantioned before, these sensors are passive, no moving parts, so what is there to fail?

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Reluctor ring?

PTMADRID said:

Hi dubble,
Replacing one or other sensor roughly every 2k miles I have never come across a damaged wire. I do use the hub/wing mounted clips to position the cable to the plug which appear to make good contact and are secure. Sprayed with contact cleaner various times. All to no avail.
Datatej, I appreciate your comment but no evidence of contact on replaced sensors, that I can see anyway.
As I have nantioned before, these sensors are passive, no moving parts, so what is there to fail?

Click to expand...

PTMADRID said:

Hi dubble,
Replacing one or other sensor roughly every 2k miles I have never come across a damaged wire. I do use the hub/wing mounted clips to position the cable to the plug which appear to make good contact and are secure. Sprayed with contact cleaner various times. All to no avail.
Datatej, I appreciate your comment but no evidence of contact on replaced sensors, that I can see anyway.
As I have nantioned before, these sensors are passive, no moving parts, so what is there to fail?

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Yes they are a passive device consisting of a coil of very fine wire, so there is potential for wire breakage.
Have you measured the resistance of a failed sensor? It would be interesting to take a failed one apart.