Disco 2 Fault : 4047 sensor right hand rear (air gap too large)

I have recently fitted extended abs wheel speed sensors in the rear of my vehicle, since refitting the sensors the 3 amigos have decided they want to be my friend again. However I am only getting the lights after I’ve drove the car for a while, sometimes I can even drive it for a good few miles before it even comes on. I’ve had it back off several times now trying to re seat the o ring in a better position each time, cleaning and re greasing the sensor each time I do. Wondering if anybody has any tips/ tricks/ or advice on this matter. Any help, as always is greatly appreciated.

(Wondering why you did this instead of cutting the wires leading to your existing ones and extending them yourself with bits of other wire.)
Nevertheless, I think we have to assume that the sensors, per se, are OK in that they send a signal to the ABS ecu on test and sometimes while running. So, if the air gap is too big it implies that the sensor quite imply is just not quite far enough into its 'ole. Which is why some people recommend giving it a bit of a tap with an 'ammer. Gently mind.

But we also have to ask how long ago the hubs were replaced. It is alwasy best, where possible to replace the hubs with new ones together with their new sensors already installed. The hubs only have to be running a fraction out of round through wear, to set the 3 amigos off.

You could try cleaning them then putting them back in dry and tight. The O ring may have swollen.
Do you still have the old sensors? Have you compared the fitted length of them with the new ones?

I'd be tempted, as it'll cost nothing, to go back to the old sensors, cut their wires and extend them a bit as first mentioned. If they work then you'll know it is your new sensors not fitting quite right.

@sierrafery will probably have something to add as he is the dude with all this!!

Hi, Stanley has covered it well already... if you replaced only the sensors that intermittent air gap fault means that there is a play in the reluctor ring or the new sensor is not 100% compatible with the old hub, fit thinner o-ring for start or get rid of it see what happens... and quit greasing the sensors, that grease just accumulates metal fiilings and mixes up the reading as the activity it's purely electromagnetic there

There was something inside me telling me not to cut the original Wabco sensors so I purchased an extended kit (open ended wires) and also purchased some more standard length ones (with plug in connections on top end) cut the connectors off the new standard length ones I bought, and spliced into one of the kits I’ve attached below, making sure that the length of the lines after soldering matched my new brake lines. I have checked the values on nanocom to make sure each wheel speed sensor was getting a signal, and all values were around 2 which from reading a couple of previous threads seems fine.

The first time I re assembled the brakes and went for a drive I had the air gap fault on both sides, I them took it back apart, re fitted both sides with more care, and the rear left has not given me any fault codes sinse, however the right still seems to hold the problem, will try fitting again without grease and thinner o ring, and also giving a bit of a tap. Will post again when I find out more.

Thanks for the replies too!

There was something inside me telling me not to cut the original Wabco sensors so I purchased an extended kit (open ended wires) and also purchased some more standard length ones (with plug in connections on top end) cut the connectors off the new standard length ones I bought, and spliced into one of the kits I’ve attached below, making sure that the length of the lines after soldering matched my new brake lines. I have checked the values on nanocom to make sure each wheel speed sensor was getting a signal, and all values were around 2 which from reading a couple of previous threads seems fine.

The first time I re assembled the brakes and went for a drive I had the air gap fault on both sides, I them took it back apart, re fitted both sides with more care, and the rear left has not given me any fault codes sinse, however the right still seems to hold the problem, will try fitting again without grease and thinner o ring, and also giving a bit of a tap. Will post again when I find out more.

Thanks for the replies too!

Didn’t want to get hasty with any conclusions on this incase my lights came back on. Like ferry said, took the sensors out and wiped them grease free, put them back in clean and dry and kept the o rings in. Took it out for a long (anxious) drive to check if the lights were going to come on. They didn’t, however I got home to notice a puddle of ace fluid under one of my rear pipes. Had to laugh or I would have cried. Have now since replaced the pipes and seals and am back on the road lights and leak free. Thanks again for the advise fellas!