project 2009 Z4 E89

[SiC]

2 hours ago, Noel Tidybeard said:

would the pas module fall under Cobbles jurisdiction of complicated shite that can be un-broken?

He probably could fix it but the problem is that it's not worth him doing it. How ECU Testing fix this isn't clear and no doubt they won't be telling anyone and its one of their cashcows. Usually there is something online on mhauto or somewhere like that too. But nothing.

My suspicion is it's possibly the capacitors (I reckon they was what was shaking around in the one I bought) coming loose or failing. Also possibly the CAN driver IC failing too. 

But the cost of a second hand unit is such that it's cheaper to do that.

2 hours ago, cort16 said:

  Pay the money 

Wait, I thought you were Scottish?! 😆

All joking aside, I fear they would want to fit a brand new or reman unit and it'll be a £k bill. 

I also think I'm close to a resolution on what the issue is - basically replace that motor/rack. It's also a well known common issue on these early ones as these on Facebook have said to me and I've read on forums.

So I'm going to at least have another stab at it with another motor/rack. 

 

1 hour ago, RayMK said:

@SiC I admire your determined and skilful approach when getting your fleet up to your standards.  Perhaps you need something French and simple* like a Citroen C6 to help you appreciate BMWs a bit more 😀.  

I used to daily a Laguna II V6 - it was one of the most reliable* cars I owned!

* It did loose a coil pack and I did have to get the ABS module replaced with a second hand unit as it was broken when I bought it.

I guess people must see a theme with car I buy. I either buy them already broken or buy them working and they break soon after I buy them. 🫠

47 minutes ago, Fat_Pirate said:

Reading this thread has led me here:

Dacia Spring 65 version.  

In all honesty I would rather catch the bus. 🙃

(Actually I do catch the bus or train to work and don't actually need a car really if I was being sensible 😄. But I'm not and it's why I have 8 cars now.)

I know a Dacia works for many people especially on here but I just don't think I could own and drive one. Not very AS I know. But I'd rather wallow in old premium cars that are a pain in the bum sometimes.

Also I rarely talk about it as there is nothing to say, but my wife dailies this. I may be reckless with my own cars but I'm not that silly 😄

 

24 minutes ago, Hertz said:

Surely if it's working intermittently then the rack rack and motor should be still ok? Must be a sensor or bad connection/earth somewhere ?

This is why I really wanted to eliminate any issues with power and signal lines in the wiring. Just so in my head I completely eliminated any possibilities of it being so. But as the FB posts above, this is a common issue with an internal fault in the modules.

Sensors is basically one that goes to the top of the rack. If this is disconnected it logs a code in the module but the module is still possible to talk to with diag tools. 

Wiring for power is basically two wires - earth and positive feed. Earth I need to have a look for but the test light looks good and the positive feed looks perfect. However the module doesn't talk to the car when it is providing assistance and when not. These EPS draw tens of amps - one of the biggest power draws in the car. So a voltage drop would be noticeable and loose assistance. But even with almost no power draw, when comms should be fine, it still doesn't talk.

Then the only other wires are two PT-CAN differential lines and the wake-up signal. Both of them I checked above with an oscilloscope. Those signals look textbook clean. Albeit not with the EPS module connected but I know the wiring is fine. Plus there is a lot of other stuff on that bus (ECU, parking brake, ABS, Instruments, etc) and none of them have been moaning about the CAN bus going down. If it did then the dash would go nuts. 

Hence really the only thing left is the EPS motor module.

Most probably would have googled this fault and sent the motor to ECU Testing or chucked a replacement on. But I really wanted to make sure that it was the actual fault and why it's been a bit long winded. I've been down this road before where everyone on the interwebs and Google say it's something but it turns out not to be!

[Dick Cheeseburger]

At this point, I think I'd be dusting off the Spitfire and driving off into the sunset, not looking back!

[SiC]

22 minutes ago, colino said:

Apologies if this has already been covered, but are the battery and alternator up to snuff?  They take a fair whack of power in operation and I just wonder if it is dropping out because it doesn't think there are enough magic pixies in the wire.

Battery isn't in the best of health - at least the car thinks it's possibly not and occasionally throws a low battery warning if I've left the ignition on too long. But then it's been replaced and not registered. So it might not be fully aware of it's capacity. 

Alternator is harder to test as BMW have gone all fancy at this age. They generally only charge when deaccelerating or steady state driving to save fuel and reduce engine power losses. Also when fully charged it will back off the voltage to not over charge it. So a basic voltage check isn't enough.

However with the ignition on standby when I've checked other modules, I am getting around 12.2v which is respectable. 

Also I would expect it to loose assistance but still talk on the CAN bus if the voltage is low. Plus give an error code. Maybe if super low (like sub 10v) it could shut off entirely but everything else at that point would be moaning too. 

So while the battery might not be in best health (or it thinks it's not), I'm 99% sure it's not that. Likewise I know the alternator is charging as the voltage isn't dropping to really low when off. 

[cort16]

At least if you take it to a BM specialist they can do the test plan on their diagnostics and give you re-assurance you're going to spend  £££ on a part and it fix the problem.   

I don't like spending money fixing cars but I like it even less spending money fixing cars then it still doesn't work.

 

[SiC]

11 minutes ago, Dick Cheeseburger said:

At this point, I think I'd be dusting off the Spitfire and driving off into the sunset, not looking back!

Even that broke on me on the first drive out after buying! 😆

That's despite @N Dentressangle daily it into Bristol on the M5!

Chucked a fancy electronic distributor on that I had on the shelf and it's been fine since.

(Albeit I think it might have been my fault)

The VP broke on me with its first drive out. Despite @Andyrew doing literal thousands of miles in it and to Scotland & back, utterly fault free. Throttle cable fixing broke off the firewall on me.

My previous Z4 needed a replacement rear caliper and pads where it seized and smoked the pad (almost disc too!)

And had to rebuild the parking brake shoes

Also reflash and code in a second hand airbag module.

Fix EML by fixing intake leaks and faulty MAF.

Repair the melted interior fan controller by soldering it in.

Replaced the thermostat. Fixed a door leak.

Then it was reliable! (Probably other bits I've forgotten I had to fix too...)

A £1200 car that became a £1500-ish car before I could trust it. But still cheap.

 

What about the 3-series? Well I bought that broken.

ABS/TCS/Cruise/etc faults were thankfully just an ABS sensor. Lucky as ABS modules are prone to failing on them and cost mega bucks to fix.

Also needed new pads+discs on the front.

Replace the iDrive unit with a second hand unit and coding it in.

And four new tyres.

Also did the aux belt+tensioner as a precaution.

Plus other things I might have forgotten.

So a £1600 car that became £2500 before it was usable. But if the ABS module needed replacing then it would be a £3500 car.

You can buy a working E90 330i for £2.5k ... However I now know it's completely sorted!

 

I could go on! Basically pretty much every car I've bought that needed fixing soon after buying. 

TL;DR cars hate me and I'm just unlucky with them. Which is why I'm pretty ambivalent that this has broken on me. Basically I was expecting something. Just I wished it waited a month or two of use first before it did. 😅

[Hertz]

Good shout re Alternator, different kettle of fish I know but about 15 years ago when we had a Ford C Max the PAS was in and out and then failed due to the alternator being goosed. Guess it's charging ok though?

[Peter C]

@SiC

The Boxster didn’t give you much grief, if I remember correctly?

[SiC]

28 minutes ago, Peter C said:

@SiC

The Boxster didn’t give you much grief, if I remember correctly?

Looking back through my images, it leaked out PAS fluid out of a hose crimp in the first month. I put a clamp on and topped up the fluid which seems to solve the problem. Replacing the hose was a massive job as it goes from front to back, so the simplicity of the clamp fix was appreciated. 

Then a few more months in and about 1.5k miles it started loosing coolant. Also had weird electrical issues where things weren't turning off. I kept it topped up and ignored the issues as the weather was nice.

I parked it up as the weather was cooling off and the leaks were getting too bad. Plus moving house around then too. Then COVID happened, so it sat longer until I could get it back from storage to fix it. 

So during a COVID lockdowns l replaced the two leaking front radiators and split coolant tank in the boot. While I was there I did water pump+aux belt+oil+filters+plugs+coil packs. 

 

 

Electrical issues turned out to be the ignition switch. So replaced it. 

After that I did 4 years and 10k or so miles mostly fault free. Front top mounts (creaking), thermostat (I should have done it with the pump) and general servicing the only things needed but that's wear and tear really.

So yeah even your Boxster that was utterly faultless for you ended up needing fixing when I owned it. Cars just hate me and I'm just unlucky. 😅

I'd say it's because I drive my cars hard (I do!) but they even break when I drive them carefully after just buying it. 

[Peter C]

2 minutes ago, SiC said:

So yeah even your Boxster that was utterly faultless for you ended up needing fixing when I owned it.

The power steering pipes issue should have been spotted by the Porsche specialist* who serviced the Boxster twice during my ownership. Luckily, the PAS system didn't give me any grief. 

As for the other issues, that's just bad luck. Sorry! 

My E46 325Ci didn't give me any grief whilst I had it (for approx 2 years). I sold it to a friend and within a few months the fuel pump packed up and the LEDs blew in one tail light. Biggest problem is the engine is now using a lot of oil, despite there being no sign of any leaks or blue smoke from the tail pipes. Whilst I had it, I didn't need to top up the oil once between changes. 

If you're unlucky, I guess that makes me lucky!

 

[SiC]

12 minutes ago, Peter C said:

The power steering pipes issue should have been spotted by the Porsche specialist* who serviced the Boxster twice during my ownership. Luckily, the PAS system didn't give me any grief. 

As for the other issues, that's just bad luck. Sorry! 

My E46 325Ci didn't give me any grief whilst I had it (for approx 2 years). I sold it to a friend and within a few months the fuel pump packed up and the LEDs blew in one tail light. Biggest problem is the engine is now using a lot of oil, despite there being no sign of any leaks or blue smoke from the tail pipes. Whilst I had it, I didn't need to top up the oil once between changes. 

If you're unlucky, I guess that makes me lucky!

 

As I said at the time, I'm not blaming you for the problems. Like I'm not blaming @95 quid Peugeot for the ones on this. 

I'm just incredibly unlucky in life. I do have some very good luck but I also have a terribly large amount of bad luck. 

Just I can't dwell on it too much. Instead I just need to get on with resolving the bad luck as best as I can!

[SiC]

And on that note, I've ordered a replacement rack.

I have been dwelling on this particular item for a week or so now. What's put me off is that it looks to be date coded as an older unit like the one on my car. I really didn't want to buy a replacement rack to have it fail on me a few months later again.

However looking at the pictures earlier, I noticed something familiar.

See the warranty label attached to the motor on the left?

Then my memory triggered where I saw it.

Ha! So it looks like this particular unit has been repaired before. Supposed lifetime warranty too. Probably to the person who has it repaired admittedly...

However it also means that this unit should (!) be a good working unit. Also £128 is a lot cheaper than £500 to send it off to them for the same job on mine. 

🤞🤞🤞🤞 this will be it.  

[captain_70s]

4 hours ago, cort16 said:

 It's a nice car so worth spending some £ on it. 

Having read this thread I'd say it stopped being a nice car when the manufacturer warranty expired...

[Kiltox]

29 minutes ago, SiC said:

And on that note, I've ordered a replacement rack.

I have been dwelling on this particular item for a week or so now. What's put me off is that it looks to be date coded as an older unit like the one on my car. I really didn't want to buy a replacement rack to have it fail on me a few months later again.

However looking at the pictures earlier, I noticed something familiar.

See the warranty label attached to the motor on the left?

Then my memory triggered where I saw it.

Ha! So it looks like this particular unit has been repaired before. Supposed lifetime warranty too. Probably to the person who has it repaired admittedly...

However it also means that this unit should (!) be a good working unit. Also £128 is a lot cheaper than £500 to send it off to them for the same job on mine. 

🤞🤞🤞🤞 this will be it.  

That’s a right result if it works out. 

[MrGTI6]

On 27/06/2025 at 18:16, N Dentressangle said:

I can't tell what most modern stuff is unless I can see the badge either.

I've got to the point where I don't always recognise the badge! Particularly when it comes to Chinese tat.

[Split_Pin]

Who buys broken BMWs 😂

Oh, wait.

To be fair mine has been r****ble for quite a few months now, after I fixed the problems (or got someone else to)

[vaughant]

16 hours ago, SiC said:

As I said at the time, I'm not blaming you for the problems. Like I'm not blaming @95 quid Peugeot for the ones on this. 

I'm just incredibly unlucky in life. I do have some very good luck but I also have a terribly large amount of bad luck. 

Just I can't dwell on it too much. Instead I just need to get on with resolving the bad luck as best as I can!

I'm not sure it's that or just that you like to keep your cars in tip top condition. 

I remember years ago a mate of mine asked me to list his car on eBay, an Alfa 156 iirc. He'd had it off a mate of mine and whilst it wasn't a bad car, I'd actually used it for a few weeks but really couldn't gel with it at all, it wasn't as he asked me to list it as "perfect, no known faults".

Knowing it was a 10 yr old Alfa with 150k on it I was a bit more sceptical so I had a good look through it first.

No major faults butt tons of niggles, window switches not working, eml on for something that would reset but come straight back, 18" wheels off a totally different car that looked good but had the wrong offset and 2 very on the limit tyres and also the usual Alfa stuff of crappy trim, few bits of lighting out on the dash etc. 

TL:Dr not all people's ideas of a "perfect" car are all the same 🤣🤣.

P.s I also sold a V6 Mondeo once that had literally given me not one second of trouble, even the cruise worked ok. Sold it for £300 with 6 months ticket and the waterpump went about 3 months into his ownership. Happens.

[Kiltox]

I think @SiC has the same affliction I do - minor stuff not working really winds me up, hence spending ages sorting stuff like the MMI screen folding mechanism, parking sensors etc on the AS bike A8. 

Main reason I had to bail from the Vel Satis - I’d have spent months and months of time I don’t have trying to make it perfect 

[SiC]

This car hates me 😆

[cort16]

FFS

[Fat_Pirate]

That Dacia is looking more tempting now, isn't it?  It's your future, you must come to terms with it.

[SiC]

23 minutes ago, cort16 said:

FFS

At least they make access simple!

 

I might try disconnecting reconnecting the sensor incase it's a dodgy contact that needs cleaning. It was a bit stiff last night so I might need a screwdriver to prise it apart. 

Might well fix it? Clearing the code and restarting the car with a decent 15 mile drive didn't have it come back on which suggests it might hopefully be a connection issue. 

[Split_Pin]

In my experience the left rear brake light bulb blowing can ping a code for one or more of the 02 sensors.

[Kiltox]

8 minutes ago, Split_Pin said:

In my experience the left rear brake light bulb blowing can ping a code for one or more of the 02 sensors.

wtf 😂 

[SiC]

17 minutes ago, Split_Pin said:

In my experience the left rear brake light bulb blowing can ping a code for one or more of the 02 sensors.

I hope not they're sealed LED and  @95 quid Peugeot put a pair of brand new units on the rear which I imagine weren't cheap 😬

[SiC]

On 01/07/2025 at 18:06, SiC said:

And on that note, I've ordered a replacement rack.

I have been dwelling on this particular item for a week or so now. What's put me off is that it looks to be date coded as an older unit like the one on my car. I really didn't want to buy a replacement rack to have it fail on me a few months later again.

However looking at the pictures earlier, I noticed something familiar.

See the warranty label attached to the motor on the left?

Then my memory triggered where I saw it.

Ha! So it looks like this particular unit has been repaired before. Supposed lifetime warranty too. Probably to the person who has it repaired admittedly...

However it also means that this unit should (!) be a good working unit. Also £128 is a lot cheaper than £500 to send it off to them for the same job on mine. 

🤞🤞🤞🤞 this will be it.  

I'm getting fucked off with Global Parts. Everything I've ordered from them has arrived completely different to what was listed. Different date codes, different condition and different part numbers. Not a single order I've have received has matched the pictures listed.

 

[SiC]

Well it talks to the CAN network and not throwing any codes. Older unit than the one on there though. 

Does prove its the module. 

I guess I might as well fit it. Debating whether to fit whole rack or just the motor. Not sure what's going to be easier. 

[Hertz]

Looks promising, fingers crossed either option gives you a result.

[SiC]

Another joyous* evening of being underneath this thing! 🫠

I did debate whether to replace the whole rack or just the motor. I decided motor which I'll explain in a bit.

To remove the motor, this front housing needs to come off.

The bolts that I needed to remove are better visible on the replacement rack. Handy sometimes having the replacement part next to you especially trying to find fixings.

I also removed the airbox for better access up top.

Five bolts and then prising the case apart. Steering on full lock to get as much access as possible and then the case zip tied onto the anti roll bar out of the way. Wasn't terribly difficult just the casing was fighting a bit from corrosion. 

Marked up the eccentric lock-ring that tensions the belt. 

Then knock the ring around to reveal a cut out section for the motor pinion.

You can see it to the left on the second hand rack.

Just three further bolts hold the motor. 

Then a half hour fight to get the motor to slide out. Again corrosion made the job harder. A lot of prising (including snapping the tip off of my favourite flat headed screwdriver 😭) it was free.

Corrosion was around this section.

Did the same to remove the motor from the replacement rack.

This wasn't as hard off the car. Also the corrosion wasn't as bad.

Then put it all back together.

Which is a bit like Haynes "reassembly is the reverse of disassembly". The damn lock ring kept falling off. There is a little pin that is supposed to hold it in place but that kept coming out. I ended up knocking it into a fresh hole around the outside.

I also had a fear that the lock ring was going to come off and jam the mechanism when driving. However after what was far too long, I realised it wouldn't as the outer casing lip was made to push it into place so it couldn't move. 

Once the lock ring was in place, a straight forward case of putting all the bolts back in. Being BMW (well ZF...) they are of course made from aluminium. I didn't go crazy doing them up as no doubt they're Torque To Yield bolts. I did them all up to 20Nm which seemed enough. 

Kinda wish I put a drop of blue loctite on them. Maybe I'll revisit them and do so. Or not as that risks them snapping if I fiddle too much.

Plugged everything back in and checked the car was happy with it's transplanted motor. It seemed to be.

In hindsight replacing the entire rack probably would have been quicker and easier. However I didn't because those metal brace sections would need to have come off. I didn't fancy my chances with those bolts whatsoever. 

Not least that if they snapped, it would not be a fun job drilling out/heating up/welding a nut on/etc on my back. Up on a lift maybe but on my driveway nah.

With such confidence I even put the under tray back on!

I bloody hope this is the last time I need to be under it for a while.

Tbh if Global Parts sent me a working motor in the first place then a lot of this frustration with the EPS wouldn't have been so bad. I ended up spending a lot more on this rack for the stupid motor than if I got a cheaper E90 LCI rack, took the motor off and recoded it. There is also the possibility that this older motor than mine will have exactly the same fault again later. If the original motor was a good part with the right part code as per their listings, I'd have had it fitted and already be in this position with working PAS last week. Rather than having to double check that it's not something else at fault with extra diagnosis.

However for now I'm just happy there is no warning lights and the PAS is working. It's a bit heavier than before when it was working but I'm hoping that's because the old one was going into fault mode which is probably full assistance. 

Also at least this is a E89 motor with identical part numbers as what has come off. Means things just work as it originally did without the faff of re-programming stuff. Plus now I have the original off, if this replacement does fail, I can send this original motor off to be repaired without making the car potentially immobile.

While I had the bonnet open, I disconnected the O2 sensor connector and gave it a good spray of contact cleaner. Hopefully that might fix that problem.

Next up will be to have a look at this roof Hall Effect position sensor. While it's not stopping the roof from working right now, it's only a matter of time that it might get it completely stuck. 

For now it feels like I'm finally winning. A few months time it'll all be forgotten.

[JakeT]

Having been 'off' for a while, I missed you buying another Z4, but well done. I agree, a rack swap would have been easier most likely, but the state of that one from Global Parts was total shit. I've bought from them before and had hit or miss, too. Annoying as they are such a big breakers that don't keep all of their parts in Latvia et al.

I did a rack swap a few years ago on a friends 130i with ePAS as his sounded like the rack was full of cement. At least on a RWD car the rack is easy enough to get to.

[N Dentressangle]

Well done.

I'm too old to do those jobs on my back with the car on stands these days, I'll be honest.