The ABS warning light came on this afternoon but the first red light I came to I switched the ignition off and back on and it went out and stayed out. Now, when I test drove the car back in December, the light came on, but when the dealer tried it there was no fault to see and obviously it has been fine since then. Is this likely to be a dodgy sensor? I have VCDS Lite. Will that be of any use in determining the problem?

Somehow this posted twice. Could a Moderator delete this post? Thank you.

Just plug in and see, if there is no light, then there is no fault unless it stores one, but that’s hit and miss. It’s possible the dealer just cleared it and hoped for the best and the same fault (whatever it was) has returned 

Do you have ABS - anti lock - function?

2 hours ago, 26DIPP said:

Do you have ABS - anti lock - function?

I have no idea. I was driving in city traffic when the light came on, I continued to the next red light, switched the ignition off and on again and the light went out. It has not come on since.

Self check happens in the first few hundred meters of driving or so, if it didn't come back you're good.

ABS became compulsory in the UK in 2004.

4 hours ago, toot said:

ABS became compulsory in the UK in 2004.

I think when 26DIPP asked "Do you have ABS - anti lock - function?", he meant was it working, not was the car fitted with it. That was how I interpreted it. I know the car has it, hence the warning light.

@adamytIt originally came on after about a mile or so of starting out. I have done a couple of longer journeys since and it has stayed out. It is possibly an iffy sensor or the toothed hub is clogged up.

As I said, it came on during the test drive and I pointed it out to the seller, but if, like me, it was out the next time the ignition was turned on, his mechanic would not have registered a fault. Neither would the MOT station that tested it before I picked the car up.

Hit it with VCDS lite, if you haven't already. 

No toothed hubs involved, the sensor looks at a magnetic ring integrated into inner face of wheel bearing.

37 minutes ago, Breezy_Pete said:

Hit it with VCDS lite, if you haven't already. 

No toothed hubs involved, the sensor looks at a magnetic ring integrated into inner face of wheel bearing.

I wouldn't know what to look for with VCDS Lite. Regarding the toothed ring, I was going by what the Haynes manual tells me. Time was you could rely on the Haynes manual for accurate information. It would appear no longer to be the case.

Just scan the ABS module, any fault codes should point you in the right direction.

10 hours ago, Jocko said:

Time was you could rely on the Haynes manual for accurate information.

Not totally my experience with a couple of 1974 and 1980 Haynes manuals.

 

As advised as you have VCDS lite you can put it to good use to help track this down, might also be a connector or wire.  As in with a neighbour's 2005 Merc but for the work involved to check the connector it might have been worth taking a risk on fitting a new aftermarket (Chinese made?) £20 sensor (keeping the original factory fitted part just in case), I don't know how it was fixed as it was done in with a lot of other work repairing and refreshing the car which must have cost a pretty penny.