DSC and xDrive intermittent failure mystery

[The Stiglet]

I recently purchased an LCI E70 X5 40d M Sport from BMW and have just returned from a 1,400 mile trip to France. Something very peculiar happened and I wonder if anyone can offer some advice?

We left from London, took the Eurotunnel and aimed for a stop off near Tours. The car was great - comfy, fast and fairly economical. We were sitting with cruise control on at a steady 85mph when about 100 miles out from Tours a DSC/xDrive failure message popped up on the Navigation screen, kicked off cruise control and gave us a fairly big jolt.

I was rather confused by this so I pulled over at the next available opportunity, restarted it and it cleared the code. I had a cursory glance around the vehicle, opened the bonnet and then decided that it must be a sensor issue. Back on the road, we lasted another 30 mins before the same failure message came up again. Not feeling particularly comfortable, we pulled over and I started consulting the Internet, which told me that DSC/xDrive failure could genuinely affect drive to the wheels as xDrive is not a fixed mechanical diff.
Caution was urged but I also checked the tyre pressures (it was hot). All of them were out - the car is on 20inch Continental SportContact 5 non run flats. Pressures ranged from 2.6/2.8 bar upfront and 3.2/3.6 bar at the rear. I wondered if this was causing some transmission issues and lowered them all to the recommended 2.2 bar.

This seemed to do the trick but it also coincided with us turning off the motorway onto B roads for the rest of our journey. Long story short, over the next 200 miles we saw no errors. The moment we turned back onto the motorway today, we started to get the failure messages again. By the time we had seven of the same messages, I gave up pulling over and restarting the car as we had 700 miles to get through. I had spoken to BMW and they assured me that I wouldn't be damaging the vehicle to get it home, nor could I really feel any changes to the drive so I took it carefully.

But the oddest thing occurred when we arrived on home soil - over the next 80 miles up the M20/M25 etc, the error message didn't return! Within 15 minutes of getting on a French motorway the car would flag a failure but nothing in the UK. So I'm guessing it must be heat related. I had thought it was a speed sensor or even a steering sensor but if we couldn't replicate it in the UK then that doesn't stack up unless heat is the issue.

I can hear some noise on the near side front hub (when not under load, it also remains constant when I put it in neutral too) so I think that's a worn bearing and could do with a replacement, other than that there's nothing obvious. I have read things about non starred tyres, particularly non run flats messing up the transfer box. I'm not sure if this could be an issue here? But the most bizarre thing is why doesn't it do this in the UK?

Thanks in advance

[anonymous-user]

Do you have very different wear on any of the tyres? Eg new on back and worn on front leading to significant rolling diameter differences (most noticeable to system on straight road at high speed)?

[anonymous-user]

Do you have very different wear on any of the tyres? Eg new on back and worn on front leading to significant rolling diameter differences (most noticeable to system on straight road at high speed)?

[.richard]

Had similar problem on Jag. Under low revs and stable throttle had the same issue in France. Driving in GB with varying conditions and therefore throttle no problem. Turned out to be low oil in auto box. No leaks and fully serviced!

[The Stiglet]

drmark said:

Do you have very different wear on any of the tyres? Eg new on back and worn on front leading to significant rolling diameter differences (most noticeable to system on straight road at high speed)?

No, they're all fairly new on about 80% tread

The dealer says that they are replacing the wheel bearings then going to road test it. Let's see what happens!

[roofer]

drmark said:

Do you have very different wear on any of the tyres? Eg new on back and worn on front leading to significant rolling diameter differences (most noticeable to system on straight road at high speed)?

Difference doesn't need to be that much either. My transmission whined for this reason, stopped as soon as I put 4 new boots on.

[The Stiglet]

I spoke to the dealer yesterday - new wheel bearings, recalibration of steering angle sensor and a new front diff! I noticed a mild shudder when under full lock and moving slowly from the front diff. I'd assumed that this was part and parcel of a heavy four wheel drive shifting power through the system but they have said that it's not normal and replaced the diff.

I do wonder whether this could have failed spectacularly on the motorway as per other reports of failed rear diffs but luckily it didn't.

Anything else I should ask them when I collect the car today? Transfer case/drive shafts?

[Shedding]

Sorry to dig out an old thread but I have recently bought the exact same type of car and it has exactly the same fault which only happens after a while at motorway speeds. Mine doesn't have any low speed shuddering or wheel bearing noise but even though I've had all four wheels balanced, it still feels as though a wheel is out of balance at around 60-70mph.

All four tyres are worn and the steering wheel isn't centred so new tyres and an alignment check is next but I just wondered if the work you had done had solved the problem for good or whether it reoccurred?

Thanks.

[Shedding]

Just an update to help someone with the same problem in the future. Over the last few months my car has had the following work and tbe Xdrive problem is solved:

• 4 new tyres (20" staggered, non bmw * rated)
• new front propshaft (bmw recall)
• 4 wheel alignment
• fixed a broken front coil spring and sticky brake caliper

My suspicion is that the problem was the prop shaft as the UJs were sloppy.

Hope this helps someone in the future