Wheel Sensor Issue?

[Blotchyprune]

Hi Guys,

My first post, IÂ’m hoping someone can help me with an issue I have...

I have a 52 plate Passat and I'm pretty sure it's B5.5, it's 1.9 TDi 6 speed and done around 170,000 miles.

The problem I have has been happening for around 6 weeks although it doesn't happen every time I drive it's more often than not...when the problem does occur this is what happens, when the car is being driven at a steady speed and I donÂ’t move the throttle the car can hold back then go again and does around 10-20 times before the ESP light comes on if I donÂ’t change the position of the throttle or change gear. If I change gear or position of the throttle it can go for a minute or two but then can start again, basically on my 10 mile journey to or from work I can make the light come on 10 times or none. When the light comes on it goes into like a limp mode but not as bad but also comes with a horrible juddering, this is reset by switching the car and restarting.

I’ve just had the MOT done and with only little maintenance the car pretty much flew through so I think it's worth trying to get this sorted, I say this as after searching around one of the reasons I read that could cause this was something to do with the breaks and could cost £1500+ a bill I don’t want to pay as the car was only £1000 when I bought it 3 years ago. However, the garage that MOT'd it also took a look at the diagnostics which didn't list any errors at all and neither does my cheapy ODB2 reader, the mechanic said he would expect the most likely cause would be a wheel sensor but as it wasn't throwing any errors how do I know which one?

I donÂ’t want to change all them if I donÂ’t have to but more so if it doesn't fix the problem, I did read the injection wiring loom could also be the cause...again IÂ’m happy to replace this if it is but as you can see I there is a lot of guess work now going on which could up hurting my wallet.

Is it possible to test the sensor(s) to see if they are faulty if it's not giving an error?

Do you think the garage I took it to is probably not using the right diagnostics kit? for the record they didnÂ’t charge me to look

What do you guys think, IÂ’m no mechanic but done a fair bit of engineering in my time so quite confident and willing to do what I can at work or at home

Thanks in advance, let me know if you think IÂ’ve missed anything that could help

[Crasher]

3B3 facelift saloon, 3B6 facelift estate, this B5, 5.5, 6 etc whatever is tosh. You shouldn't, really cant, base the cost of repairs on a cars value, you could easily get to the point that a tank of fuel is more than it's worth, it was a £20K car new and it is still a £20k car and cars don't get cheaper to fix as they age, on the contrary. The clue here is the ESP warning, on these later 3B's they have a combined yaw and acceleration sensor under the back seat and these are notorious for going wrong, part number 8E0 907 637 A and they cost £978.11 inc VAT but there are loads on fleBay for pennies. This sensor detects movement and the ABS pump in combination with the wheel speed and brake pressure sensors can detect if the car is out of control and apply the brakes individually to try and stabilise the car, unfortunately when the sensor sends incorrect data it can make the car twitch about, reminds me of a certain Boing aircraft that was too clever for its own good.

[Blotchyprune]

Thanks Crasher,

I thought the more info i gave wouldve been more helpful but i geuss when it's sensors that can be irrelivent in most case's

I can see loads of these all at a cost i dont mind spending if it crosses of the list, i have no problem with the value of the car and probably shouldnt try to compare but i do think a line can be drawn sometimes

I'll see how i get on with changing this YAW sensor and hopefully report back with good news

Thanks again

[Crasher]

I have just pumped £5k in parts into my 2003 Octavia, it is such as good car that I could not think of anything I would want to replace it with. Someone in the office worked out that the amount of time I put into it would have been charged out at £12k in labour alone! At a few £'s changing that sensor as a test is a cheap test but it has to be calibrated so you will need to find someone who can do that.

[philipharmes]

Have you checked the carpets front & back for water.
There is thick foam insulation under the carpet, so it won't always be obvious.

When the plenum chamber ( where the battery & servo sit ) swimming pool gets full it can overflow into the interior.
Cables & sensors under the carpet get soaked & give spurious electrical responses.