Intermittent Power Steering Failure

[Z4Mattt]

My Z's power steering is failing from time to time. Of course I could replace the whole steering column, but that's at least £1.5k (!) and I'm not entirely convinced a whole new column is needed just yet - was hoping to get some opinions from those more knowledgeable than I...

- It fails from time to time. On short journeys, it generally doesn't fail! It's tended to let me down on longer journeys, then fail for ~50% of the time I'm on the week away. Then, I come home, leave it for a few days, and it seems alright again.
- It fails in stages. Usually I get 'Steering Assistance Faulty' warnings - which make the steering heavier but there's still some assistance - then I get 'Steering Assistance Failure' warning - which means it's fully dead and really heavy (parking is a nightmare!)
- Turning the car fully off and on again sometimes completely fixes the problem and it comes back to life
- It has gone months without doing it, then recently it's become more common

Here's my understanding so far:
- Could be a battery issue, so I replaced that with a new Bosch one recently. Unfortunately didn't help (though I'm happy with the new battery!)
- From reading around on Google there are other things that could be at fault, incl. dodgy fuse, loose sensor connectors under the steering cowl, dodgy alternator not providing enough power etc. - but I don't know enough about the mechanicals to get to the bottom of it.

Any thoughts would be much appreciated...!

Cheers,
Matt

[2011 e89 23i M-Sport Manual]

 

[Anonymous]

So what model and when was your E89 built?

How many miles?

Have you access to a code reader?

Issues with E89 steering are much less common that E85..there was a duff batch made at one point..

Once the codes are read your next actions will become more obvious ..

 

[Z4Mattt]

2011 23i MSport, 63k miles.

No access to a code reader - but I did take it into my local 'BMW specialist' to read the codes and they effectively just recommended a full replace of the steering column. All I could see from their report was the codes saying the power steering failured, nothing more granular, so it felt a little like they might just be wanting to get the £££ business of a full replace.

Perhaps I should take it to a main dealer for diagnostics...

 

[flybobbie]

Get under car take cover off. The connectors are exposed to the elements.
Try cleaning those with contact cleaner.
Worth a try.

 

[Owdgit]

Have a look at this thread, might enlighten you
https://z4-forum.com/forum/viewtopic.php?f=45&t=123132

 

[Zforbes]

I've been having similar issues, like you but probably more frequent. I've replaced the battery cleared the codes then after a day or so had the ping again.

I've downloaded INPA and bought a connector so I could read the codes, but couldn't clear one of them until I pulled 2 fuses associated with power steering. Had a message after that to reset my clock so I must have cut power totally, after that I plugged in again and managed to clear all of the codes and since then I've been everywhere with short and long journeys upto an hour constant driving. I had booked a slot at my mates garage on Friday to remove the motor and send it to ECUTesting for refurbishment. I've since told my mate not to hold the ramp and I'll let him know when I get the error again.

Fingers crossed it won't happen again and it was just a battery issue anyway, just needed to discharge it before resetting maybe.

I am however expecting a ping at some point so I'm transporting my laptop and cable around just in case and at that point send the motor away for refurbishment.

It's worth keeping this thread going until you manage to resolve for future reference of others

 

[wanatkinson]

I had initially posted this here: https://z4-forum.com/forum/viewtopic.php?t=120440&start=15 but this seems like a better place.

So, I discussed my EPS issue via the above link last year. I didn't actually get it to a garage until this year. Initially he checked it over, resat the cables and whatever and gave me it back, saying it would be really expensive to fix. I suggested getting the ECU refurbed which he said he wouldn't normally do and wasn't keen as it would tie up a ramp for a week or whatever (it is a small garage). Anyway, the problem came back after a week or two so I had to take it back.

He said he would have to replace the rack as the ECU couldn't be fixed and the BMW price was going to be £1700 for a replacement but he would see what he could do but he was difficulty finding a cheaper alternative. He eventually sourced a EPS from a 1 Series which he said is the same as the e89. Cost: £250 + labour. Great.

First problem: Sport mode no longer stiffens the steering - Is this because 1 Series doesn't have Sport mode?
2nd problem: Slightly pulling to the right.
3rd problem: After a couple of months of occasional driving, the problem has returned, exatly the same! Intermittent dead steering (the condition changes at start up although the bonging noise and warning light can come on while dirving and the power remains until resart).

I changed the battery a couple '000 miles ago. Interested to hear what anyone thinks the problem could be (coincidence?!) and what I should do next. I don't have the tools or space to work on the car myself.

Edit: I connected my C310+ scanner and it can't communicate with the EPS module. Everything else works with the scanner.

 

[wanatkinson]

Possible cause: dodgy ground to the chassis causing high voltage on the comms wires , possibly frying the motor electronics.

https://www.youtube.com/watch?v=S5QXRNKRweY

 

[wanatkinson]

Update: got the car back from the garage. They fitted "another" one for free. It doesn't pull to the left but, strangely enough, this one doesn't have Sport mode either. The guy said he doesn't know what it does..I'll live with it I guess.