2004 Z4 Electric Power Steering / Warning Light Grief

sprice

New member
From all the searching and reading I've done, early Z4 electric power steering seems to be a right nightmare, but I can't find my exact problem anywhere... so thanks for reading this far, and hopefully I can get some pointer(s) here...

I bought an '04 Z4 several months ago. Seemingly all good at first. Then, intermittently at start up, the EPS warning light would stay on, and there wouldn't be any power steering. I'd turn ignition completely off, remove/replace key, then turn back on. Sometimes this would "fix" it immediately; other times I'd need to repeat the process. It has taken up to 6 off-then-on attempts. It seems to happen whether the car's cold or hot, first thing in the morning or otherwise. The originally-intermittent nature is now pretty much every time.

After trying to fix the problem, and being unable to find the cause, the selling garage suggested a workaround - pause during ignition-key turning and let the lights go out... then start the engine. This works most of the time; other times I need to repeat the procedure. Other times still, I can start the car this way and the warning light will be off; I'll then do some slow manoeuvring (typically multi-degree steering wheel turns, if not lock to lock) and the EPS will suddenly "kick in" and practically yank the wheel out of my hands. The EPS warning light will come on around this time, then go back out, and I can drive away as if no issue. Other than as just described, the EPS light and issue has never appeared whilst actually driving.

Searching the internet I came upon the Z4 "sticky steering" issue. I've got that too - driving along, the EPS will be causing the steering wheel to "twitch".

According to the selling garage, they've approached BMW who weren't able to suggest a problem/solution. From my research though, that seems a standard response.

My perception is that the selling garage needs some help progressing this matter, hence this post. The plan is to get this sorted under their insurance-backed 3 month warranty. The car also came inspected/validated by the RAC. I've dug out some PUMA references from z4-forums (12229811, 5403852, 5387507 and 5161146) in order to guide further.

That's pretty much the nub of it. Does anyone have any advice/thoughts on the matter please? Many thanks in advance.

Steve
 
Firstly welcome to the Forum :thumbsup: Unfortunate that your first post is to report a problem. Looks like a 'selling garage' responsibility to me and as farmer suggest without a solution (and the workaround suggestions is quite frankly ridiculous :thumbs down: :x ) I would suggest a letter to the garage requesting a fix under the terms of the 3 month warranty. Record every contact with the selling garage and put all requests, concerns etc in writing just in case you need to pursue later.
 
Sorry for your troubles.

Do you have any written documentation showing you notified them of this issue within the 3 month period? If so, do as nfarmer recommends, not fit for purpose. Otherwise about all you could hope for if you do not have your own warranty coverage is some sort of goodwill gesture.

This is not the classic sticky steering problem, so PUMAs may not have any bearing. In any case, they are only informational at best, they do not imply any obligation for similar resolution. If you can find related SIBs you would have expectation of resolution as specified in the document.

Practically speaking, there should be some error code(s) stored giving more detail about what the problem is. Unfortunately, short of replacing the entire column, the only replaceable part is the steering angle sensor. If the entire column needs replacement, beware of breaker sourced columns. They must have a locking pin installed before removal. The pin can never be removed until the column is properly reinstalled in a vehicle. Failure to do so will likely damage fragile internal wiring. While seeing that the pin is installed is a good sign, you can't know that it was installed before removal or after damage had already been done unless you or someone you trust actually did or witnessed the removal and had physical control of the column the entire time.

The whole thing is a complete nightmare, so if at all possible...not fit for purpose!
 
Many thanks for your responses nfarmer, AlanJ and bcworkz. Thanks especially bcworkz re' column replacement info' - very useful, if it comes to that.

Yes, I made sure of written evidence of notification within the 3 month warranty period, and I've been documenting subsequent communications.

I've been told that no error codes are evident. That said, I've read that best/high spec' diagnosis kit is needed in respect to Z4 EPS issues. So I've relayed that viewpoint and have been assured kit is good.

It's a shame - by and large I am enjoying the car. I need to speak again with the garage, obviously. I'll post what happens so others might benefit.

Cheers

Steve.
 
Hi steve,

I've had the same problem or a while nw was bugging me for ages. Took car for service at specialist they plugged it into bosch diagnostics and told me its a yaw sensor underneath the passenger seat thats throwing the EPS module off. All the ABS/EPS and DSC modules are linked. One small sensor fault for one can cause a fault in an opposing module.

Worth getting it plugged in somewhere with bosch equipment. Normal diagnostics software cant access anything other than the engine ECU. Bmw told me they only replace on average 1.6 steering columns nationwide

Hope this helps.

Ian
 
Steve,
I know it's been a few years since you posted the EPS issue. I have owned my 2004 E85 for 7 years and now I have the exact same EPS issue.
Can I ask the statue of your EPS problem? Did you ever get it resolved?
Thanks
Bill
 
I too have the exact same issue. 2004 E85, I bought it three years ago and it had the issue then. It hasn’t worsened, in fact it improved a bit when I replaced the battery. My guess is somehow the faulty component (yaw sensor?) takes a second or two to wake up. Has anyone else found that this yaw sensor is at fault? I have no idea which garages near me have this Bosch unit, if any. I’m willing to take a chance and replace the yaw sensor if others can confirm this was the underlying cause.
 
A yaw sensor problem would almost certainly bring on the DSC light, so if you don’t have that lit up on your dash I think it’s highly unlikely. I do think INPA can communicate with steering ecu though so I would certainly try running that for diagnostics.

My best guess would be steering torque sensor or the steering ecu itself (ECUtesting could possibly repair the latter)
 
Well firstly welcome to the forum TonyV. :thumbsup:

I don't know if it may help, but EPAS issues have been ongoing for years so this thread may be worth a (longish) read:- https://z4-forum.com/forum/viewtopic.php?f=3&t=100725&hilit=sticky+steering

And I'm sure an introduction in the Newbies section of the forum would be appreciated, especially if it included photos of your Z4!
 
Thank you for the welcome. I'll post a proper intro once I get her washed and waxed for the weekend.

Thankfully I haven't had any of the sticky steering issues, even in the hot Southern California summers. The warning light on startup is the only issue with this car. It's just a minor annoyance but I'm thinking about selling the car to move to an E89 so I'd like to make it perfect. I'll look into setting up a laptop with INPA and see what I can find.
 
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