E46 DSC fault - any ideas before I see my dealer?

[Fun Bus]

Have just turned into my road and the car beeped at me and is now showing the DSC and brake warning light in amber.
The manual doesn't say a fat lot and Google will be my next call but would also appreciate any advice on what it could be?

[Sticks.]

Similar came up here http://www.z4-forum.com/forum/viewtopic.php?f=2&am...

Didn't do the diy myself. Worth noting (afaik) your dsc and dtc won't be working while the lights are on.

Someone with more knowledge than me will add to this, I'm sure.

[Fox-]

It could be an absolute myriad of different things - some requiring a simple reset of the fault codes, some requiring a replacement DSC hydro unit. Without looking at the codes its pretty hard to say.

[Fun Bus]

Totally get what you're saying Fox, it's like a needle in a haystack without a fault code.

[TheEnd]

I'll take a guess at 5E20 pressure sensor 1.

There are two screwed into the master cyl on E46s, both the same but an inch or so apart.
1 tends to be the most common to go, but either way, it's only going to need one in slot 1 or 2, but....

code read first to check before buying and trying.

[blondini]

Is the steering straight? I ask because my e46 gave same warning lamps when a failed rear trailing arm bush cocked the steering.

[ghibbett]

I've done a fair bit of research into this recently. There are also a few recent threads regarding the same issue within the M Power forum.

Anyway, the cause is likely to be any of the following:

1. Wheel speed sensors dirty/failed.
2. Steering sensor out of calibration/failed.
3. Pressure sensors failed.
4. DSC unit failure.

On mine the pressure sensors are intermittent an will get them both replaced later this month.

The easiest way to diagnose the issue is get the codes read. Come back on here with the info, or alternately put the code into Google and you'll get a host of info.

Let us know how you get on.

Edited to get rid of the silly iPhone symbols that don't work :-(

Edited by ghibbett on Friday 9th September 10:29

[Gaygle]

I bet it'll be the steering wheel sensor.

I've had this pop up twice in my 2 years of having my E46. First time was about 2 weeks after i got the car and i **** myself. Turned off the engine, turned it back on and it was gone. I got the codes read and it turned out to be steering wheel sensor that threw up the error.

Didn't see it again for about 18 months, then it came on again. Turned off the engine, and turned it on again and haven't seen in in nearly 6 months.

Sometimes sensors just throw up anomalous errors - i would monitor it for a while and if it doesn't come back on - put it down to a anomalous reading. There's no point going balls out and paying hundreds of pounds to a dealer if it was just a sensor error.

[blondini]

ghibbett said:

•Wheel speed sensors dirty/failed.

I think you would get a red ABS warning lamp as well as the others which the OP has if a wheel speeds sensor was down. Agree with all the other points but steering misalignment caused by suspension problems can also be the root cause.

[dooosuk]

someone said:

Steering sensor out of calibration/failed.

This was my issue but happened in the snow last year. Calibration just needed resetting.

[ghibbett]

Gaygle said:

There's no point going balls out and paying hundreds of pounds to a dealer if it was just a sensor error.

But the problem is how does the OP know if it's a dicky sensor or not? Remember that when the DSC & handbrake lamps both illuminate to inform of a fault, you are driving without TC, DSC and most importantly ABS.

If you're on friendly terms with your dealer, they may read the codes for free. If not, it may cost you approx. £60 but at least you will know what caused the issue and any preventative / repair work required. Alternatively there's plenty of OBD code readers available on Ebay for around £20.

[Gaygle]

ghibbett said:

But the problem is how does the OP know if it's a dicky sensor or not? Remember that when the DSC & handbrake lamps both illuminate to inform of a fault, you are driving without TC, DSC and most importantly ABS.

If you're on friendly terms with your dealer, they may read the codes for free. If not, it may cost you approx. £60 but at least you will know what caused the issue and any preventative / repair work required. Alternatively there's plenty of OBD code readers available on Ebay for around £20.

Like i said, he can turn off the engine and restart and keep an eye on it. If it comes on again in the near future - get it checked out at a BMW Specialist (i wouldn't pay BMW £60 for a fault reading, which is something that a good specialist can do for £30).

Of course, if the light doesn't go away when you restart the car - then yes, take it to be looked at ASAP. But my experience is that the DSC+TC+ABS+EBD systems are made up of many many different sensors, and all it takes is one of them to provide an anomalous reading just out of range and you'll get these lights come on.


EDIT: P.s. I'm not sure - but i think you can recalibrate your steering wheel sensor by starting the engine, then full locking the wheel to one side, then to the other. Don't quote me on that though.

EDIT 2: From looking around, it seems that is false - the steering angle sensor needs to be calibrated by a specialist/dealer (if you need this)

Edited by Gaygle on Friday 9th September 11:03

[Fox-]

Gaygle said:

I bet it'll be the steering wheel sensor.

This caused it on mine as well. Light came on, drove home, connected the laptop, read the code, reset it, it went away.

This was in 2009. It will obviously come back and require a new steering angle sensor now I've said this

[blondini]

ghibbett said:

...when the DSC & handbrake lamps both illuminate to inform of a fault, you are driving without TC, DSC and most importantly ABS.

Not without ABS, there's a separate warning lamp for that. I double checked that ABS was working when my e46 threw the DSC and handbrake lamps at me.

[Fun Bus]

Thanks for all the input. Covered 140 miles yesterday and the lights haven't made an appearance again so I'll see if it does happen again and take it from there.

[obscene]

I'll echo I had similar once. DSC light came on while driving home. Drove up the road ready to goto BMW and it disappeared before I got to the end of the road and has never come back!

[LC23]

I had this as well once. Turned the car off and left it overnight. All fine in the morning and it never came back. I would also just wait to see if it came back.

[srooks]

Had same issue recently on an e46 M3.
Fault code was 5e20.

Cause was a faulty pressure sensor (ABS/DSC unit). New part was around £80 + 1hr labour.

S