Warning Lights

I have a 523I E39 and the ABS & ASC warning lights have come on together twice in the last 2 months, but after parking up for the night, they have then gone out.

Any ideas what could be causing this

Edited by 496NFP

Andrew Rolland wrote: You need to get a diagnostic check done to find out exactly what is the problem. Most likely you have an intermittent fault with one of your wheel sensors.  I had this with both front wheel sensors on my E39. If you have a fault with your speedo it is the nearside rear (or is it the offside?) if it is an auto and you have a rough transmission shift then it will be one of your front wheel sensors. Refitting a front wheel sensor is an easy diy task.

Welcome to the forum.

Having the ASC/ABS and transmission warning lights on could be anything.  You need to get the car to a garage that can plug in a diagnostic machine that can read the fault codes.

However I would strongly urge you to phone garages first to ask them if they can read the diagnostics on your car as you do not want to be driving it unless you really have to.  In limp mode (I am assuming you mean the autobox warning light is on too and hence the transmission is in limp mode) you only have 3rd and 4th gear and reverse.  You are pulling off in 3rd gear which is why it is "heavy taking off" and you will be slipping the clutches within the autobox as a result which is never a good thing.

Did you get any other warning symptoms?  I'm suprised if everything just fell over at the same time.

A garage will be able to read the fault codes for the transmission too but it is unlikely that they will have the knowledge and tools to work on an autobox.  So you will need to go to a transmission specialist if throws up transmission fault codes.

A decent transmission specialist will also have the diagnostic gear and will be able to read the fault codes.  I can recommend a transmission specialist in Glasgow if you are from the right side of the border.

HTH

Andrew

Sounds related.  A weak battery can also help with making the car suffer from electrical faults.  My E60 won't let you drive it if the autobox isn't getting enough electrical power.  The autoboxes in these cars are all electronically controlled.  No 12 volts and it will just refuse.

My wheel sensors failed indicated by the ASC/ABS light on.  I would then get a rough transmission shift.  The front wheel sensors feed into the ECU for the autobox to tell it what speed the car is doing.  If the ECU doesn't know what speed to car is doing (as the front wheel sensors are knackered) the autobox won't know what to do either and throw its toys out the pram and fire off the warning.

A specialist or BMW will tell you the fault.  Some garages really struggle to diagnose the car.  It could be the software they are using or plain and simple operator ignorance.  If they don't know the quirks of the car they are trying to read then the games a bogie!  I've come accross both.

My local garage could read my E39 and told me which sensor was at fault.  A trip to ECP fork out 50 something notes and I had the sensor fitted within 30 mins.  Drive the car, ASC/ABS light still on then the system realises that it is now getting a signal and resets itself.  No need to get the diagnostic machine back out to clear it.

HTH

Andrew

It might not be a wheel sensor, that is why you needed to get a diagnostic check done.  E39 wheel sensors are a weak point but not always the culprit.

The garage I went to is in Bridge of Weir, about 10 miles from Glasgow Airport, so not exactly on your doorstep.

The ASC shut off valve sounds a possible cause of your problems.  If it were faulty it would certainly fire off the ASC warning light.

Did he give you a price for a new ASC shut off valve? 

I can't think how an ASC fault would trip off the transmission fault....although wheel sensors would provide an input for the ASC system.  If the ASC system is not getting input (from the wheel sensors) then it might throw off it's own diagnostic log, but the real problem may be a wheel sensor. 

If a particular component is faulty it may casue others to then subsequently fail (if they take an input from the first faulty component) and they will then log their own fault codes which may then hide the true fault.

BMW will of course be able to pinpoint the fault with their diagnostics.  For your age of car the cost will be reduced.  They charge 1 hours labour for a diagnostic check, although my local BMW dealer includes this in a service for about £20. 

I had the exact same symptoms last year, and was reoccuring intermittently, seems worse when the roads where wet.  Later a quick diagnostic suggested front drivers abs sensor.

Was about to buy a new sensor but took a look first and glad I did, the sensor has a barrel connector in the wheel arch that is in a small black box with a flap type door on it, turned out it was full of dirt and as soon as it got slightly wet was shorting the connection out.

After cleaning it out and spraying WD40 all of it the problem was sorted .....all for free.

Got to be worth a look just in case its the same thing.

Jeff

Why did you send off your ECU if the fault was showing back to the ASC shut off valve?

BMW diagnostic is usually spot on, did they suggest to repair the ECU?

sounds weird to me. dunno what to share with you.

What symptoms or warning lights did you have?

Has the car been to a mechanic that can plug in a diagnostic reader as mentioned above?

It needs a diagnostic check, anything else is just guess work and money down the drain if it isn't at fault.