project 2009 Z4 E89

[SiC]

I really should get a better car raising solution. I'm annoyed I missed out on the scissor thing that was on roffle the other day on here. Would have been perfect. 

The easier solution is to chuck it at a garage. Except by the time I've booked it in, waited to get it in and then the hassle of getting it over there, I've long finished the job. Just it takes time from other stuff I should be doing like the Midget and odd jobs like getting power down to our summer house.

[SiC]

Drove it to the gym.

No codes or lights! 🎉

 

Came home from the gym. Started it up and had this come up on the dash.

It doesn't need servicing as that was reset recently after it was done. It goes away after a restart.

My only suspicion is either the hard top warning I get when closing or a another code I have got in the instrument cluster.

Googling that instrument cluster code suggests it's usually related to battery issues. So I'm giving it another go on the charger to make sure it's fully topped up. Once this fast charger is complete, I'll put the (slower) CTEK on and put it on reconditioning mode to make sure all the cells are fully balanced.

The battery isn't an AGM when it should be. So perhaps that's not helping. A new AGM battery in the right size is around £130 and I've spent a bit too much on this already this month. So it might have to wait.

Also had a quick look at the hard top code. 

This is the service position for them.

Broom holding it open will be a familiar touch for MGB owners. Slightly different with these as it drops not from flimsy bonnet props but because the hydraulic pressure drops.

The sensors mount on the ram. There are two and I need a Google to figure which is which.

Having a quick look at them visually they seem okay. Slight crack in the casing of one but nothing terrible and not near the potted section where the sensor is.

Also disconnected and gave the contacts a good spray. 

Keen eyed people will notice the connectors above have one pair that are all white while the other is a black into white. Presumably factory is white and a sensor has been replaced before.

Cleaning the connector and reseating things didn't fix the code unfortunately. Which suggests the sensor maybe at fault. I might pull the connector apart to double check it's making good contact and bend the contacts closed more. But it'll probably need a new sensor.

How much is a new sensor from BMW?

 

 

 

£190 (!)

However if you get the identical sensor that's on a 1 series convertible it's £16. Just no connector on the end. So most now either buys the connector (~£8) and crimps it on, or chops and solders onto the old connector.

You can imagine what my plan will be for £190 versus ~£16 to £25....

[N Dentressangle]

13 minutes ago, SiC said:

Except by the time I've booked it in, waited to get it in and then the hassle of getting it over there, I've long finished the job. Just it takes time from other stuff I should be doing like the Midget and odd jobs like getting power down to our summer house.

Yep, that's often why I do stuff myself on moderns. 'My' garage is booked up at least 2-3 weeks in advance.

[Kiltox]

That’s a good result on the steering even if it is otherwise an ungrateful bastard 

I do reckon that battery is causing you trouble. 

[IronStar]

I love hardtops, they are so much more practical than softtops. However, all these sensors give me THE FEAR, and having the roof fail in half-open position on 307CC when fluid leaked out didn't help my fear of them.  I always liked convertible BMWs, but I think that having an Italian moneypit is enough, no need to push luck with German premium* vehicle as well.

Great work on the car so far, and great result on PAS!

[SiC]

Removed the rear tail lights yesterday. I was reading a forum post elsewhere on areas of water ingress. One of them was that apparently the original lights have three mounting holes while the new replacements only have two. I know these have been replaced due to the old ones having defective indicator LEDs. 

A tad fiddly job as you can't remove the rear plastic inside covers with the roof not in a service position. Bizarre but I'm kinda used to it with this car now 😅 As the battery was disconnected and being charged, there was no chance of opening it. Managed to push the plastic out enough to get a spanner in and undo the 8mm nuts.

I covered the extra hole with a bit of silver foil tape. Directly under this light, in true German electric fashion, is the Convertible Top Module. Something that really doesn't appreciate water getting into it.

Had another poke around on these sensors while the battery was disconnected too. I couldn't see any issues with them. Both sensors gave a similar resistance which isn't indicative of a working sensor but suggests the wiring to it is fine.

The sensor giving an error code has a 2021 date stamp on it. So definitely not original.

 

Later in the evening I reconnected the battery as it was pretty much fully charged. Probably could have had a few more hours on reconditioning mode but tbh it's probably just gassing more than balancing. 

Gave the roof a run. 10 runs in fact! Zero codes and zero warning light 🎉

So either removing and reseating the sensor has fixed it. Or what I think is more likely that the fully charged battery has fixed it. My suspicion was always that the roof operating a bit too slowly caused the module to not have the sensor actuate quite at the right time and upsetting it. 

Watching live data on diagnostics, everything changed plausibly. 

 

Car has just three codes at this point.

Bottom one is an air quality sensor. This detects if the air is polluted outside and if it is, turns on air recirculation automatically. These sensors always fail at this age car. My 330i has an identical error - I even replaced it with a known good sensor which failed after a few months too. So I'm going to ignore this error. No warning lights for it either.

Climate control had two codes. First was for the air pollution sensor fault as it wasn't getting data from the other module - code lost when I cleared the codes on it. This second is the blend door that distributes hot or cold I believe. I'm hoping a recalibration might fix it. I can hear the motor moving back and forth as I change the temperature, so it can't be too much of an issue...

 

Mrs SiC took it out earlier today - I assured her that it should be fine and not give any issues ... 5 minutes she reappeared. 

Engine light had come on 😆

O2 Lambda sensor again. I cleared it and told her that it's not an issue - just the same fault as the other day. I guess I'll be replacing that sensor soon.

Also there sounds like a ghost in it at lower speeds. I went out with her later on and basically the noise is the fuel pump as I could hear it clearly through the filler cap 😬🫠 

Googling Z4 E89 fuel pump noises, it appears to be a quirk on these that they're often noisy. BMW put out a software update early on that supposed to have fixed it but many still complain. I've seen old forum posts from 2010-2014+ where people have been arguing with BMW warranty about getting them replaced. To begin with people were successful but the later on BMW said it was a non issue. 

So I think it'll just be a quirk to live with. A replacement pump assembly looks like it's only obtainable from BMW for £500. No aftermarket availability. Quite a bit job to replace too. Not a tank drop thankfully but it's still an exhaust drop and heat shields. Probably alright on a lift but a nightmare on axle stands and on your back. 

It only does it at certain times too. I know these pumps are software controlled with its own module (of course it is!) and no doubt it changes pump speed depending on load. So must be at certain engine demand levels the pump happens to be running at a set volume and resonating or something like that. 

Anyway I think I'm nearly there with this car now and got all the faults out. At least everything that are show stoppers. Only one really left is a wheel alignment. It's not tragically out but it's a fair bit out to be annoying. Might also get an air con regas while I get that done. Works fine but a bit noisy. Rather make sure it has all the gas than being low and buggering the compressor.

[SiC]

Roof works off the key again now that it's got a fully charged battery and no roof error codes. 

Could they have designed a more complicated roof? Pretty sure all the BMW engineers were still drunk from an Oktoberfest when they drew this design out. 

 

There is nothing possibly can go wrong with this at all. They were so confident of that, they didn't design in a manual override mechanism if it fails either. 

[JakeT]

The roof really is mesmerising, but as you say, definitely one or two too many in the Biergarten before designing it. I'd quite like to get one for my mrs, she had a 2.2i Z3 auto some years ago and loved it. The only real issue she had with it was the lack of A/C, which was an option on the Z3 in its entire life. A nice Z4 23i would do her just lovely. But spending the money would be the biggest issue, she's rattling around in a Honda Jazz Si (wow) she was given, and is fine with it. Mainly because it costs SFA to run.

 

Hopefully a fresh lambda sensor keeps the EML off and you'll be getting flies in your teeth with glee!

[SiC]

34 minutes ago, JakeT said:

But spending the money would be the biggest issue, she's rattling around in a Honda Jazz Si (wow) she was given, and is fine with it. Mainly because it costs SFA to run.

Nowt wrong having your missus driving a boringly reliable Honda, especially when also owning BMWs!

Sounds like my Z4 E85 would have been perfect as a third car for you. Insurance on that for me was like £180 (this E89 is twice that), working air con and a whole lot simpler+easier to fix than this newer one!

[SiC]

Just been out on a run to the beach this evening in it. It's really not a bad place in the world to live.

Car ran fine. EML pinged back up again on the drive back. I haven't read the code but pretty sure it's that Lambda still. Doesn't clear on a restart. Going to just ignore it for now and hope it self fixes* (probably won't).

Fuel pump is definitely audible. Not sure why I didn't hear it before. Maybe it's worse now it had a full tank? Definitely the fuel pump as you can really hear it with the cap off. 

However all the power is there so it can't be that problematic. Plus MPG is not awful. This is me not even trying and a few spirited accelerations. 

Not very Autoshitey and much more a poor man on Pistonheads but I think my driveway is pretty cool right now. I guess they were probably competitors of each other when they were new?

[JakeT]

8 hours ago, SiC said:

Nowt wrong having your missus driving a boringly reliable Honda, especially when also owning BMWs!

Sounds like my Z4 E85 would have been perfect as a third car for you. Insurance on that for me was like £180 (this E89 is twice that), working air con and a whole lot simpler+easier to fix than this newer one!

Civic estates rock. A friend works for Honda UK (formerly Honda Swindon) and they had a few estate civics as factory runabouts. The 1.6 diesels would do legendary fuel economy, while not blowing up like the DV6 of doom. I do find the seating position a little strange though as the fuel tank is under the front seats to facilitate the cool folding rear seats.
 

Funnily we do have a third car, an E36 320i auto. She loves an auto, so this is our one car that is. In terms of simplicity there’s just about nothing simpler, and I even insured it for £120 this year. Madness!

 

 

[cort16]

Well done on sorting the steering you've probably saved yourself a small fortune.   I would get a new battery in it when you can BMW's seem to be especially grumpy when their batterys are on the way out. 

[Brigsy]

Great job on the steering repair. Ive not worked on any bm's of this era before, didnt expect to see a belt on the motor/rack for assist!

[Jenson Velcro]

Fantastic stuff. Really pleased that you’ve managed to sort diagnose and then sort the problems.

[SiC]

On 07/07/2025 at 13:23, cort16 said:

Well done on sorting the steering you've probably saved yourself a small fortune.   I would get a new battery in it when you can BMW's seem to be especially grumpy when their batterys are on the way out. 

This is a genuine new BMW OE rack:

https://www.sytnerstevenagebmwparts.co.uk/p/BMW_2009_Z4-23i-Convertible/RP-steering-gear--electrical/132019230/32106872482.html

This is a remanufactured BMW OE rack direct from BMW:

https://www.sytnerstevenagebmwparts.co.uk/p/BMW_2009_Z4-23i-Convertible/RP-REMAN-steering-gear--electrical-REMAN/132019239/32106874244.html?clickSource=relatedProduct

Basically £3k or £3.6k. I'm pretty sure a main dealer and specialists would only be fitting those bits!

Battery is something I always say to myself I probably should change. But once charged if I regularly use a car they seem fine. Especially as modern cars with a battery management system seem to be pretty soft on them. Like my 330i probably could do with a new battery but like this, now it's had a good charge, it seems quite happy at the moment.

[cort16]

15 minutes ago, SiC said:

This is a genuine new BMW OE rack:

https://www.sytnerstevenagebmwparts.co.uk/p/BMW_2009_Z4-23i-Convertible/RP-steering-gear--electrical/132019230/32106872482.html

This is a remanufactured BMW OE rack direct from BMW:

https://www.sytnerstevenagebmwparts.co.uk/p/BMW_2009_Z4-23i-Convertible/RP-REMAN-steering-gear--electrical-REMAN/132019239/32106874244.html?clickSource=relatedProduct

Basically £3k or £3.6k. I'm pretty sure a main dealer and specialists would only be fitting those bits!

Battery is something I always say to myself I probably should change. But once charged if I regularly use a car they seem fine. Especially as modern cars with a battery management system seem to be pretty soft on them. Like my 330i probably could do with a new battery but like this, now it's had a good charge, it seems quite happy at the moment.

3 grand rack on a 4 grand car good work BMW.  A specialist would fit second hand rack they'd just not warranty the work..

[SiC]

It's been a busy car weekend! Not for repairing them but for gawping at them for a change. 

With the stonking hot weather, it made sense putting the Z4 through its paces. Roof down almost all the way with the air con on full made it quite a pleasurable experience without melting in 30c+ weather. I do hate leather in convertibles and my back was soaked at times. Fabric seats are much better imo.

Covered a good 350 miles without a single hiccup. I cleared the EML at the start and it didn't come back on. No doubt it will at some point but I don't really want to spend £80 on another Lambda sensor to fix an engine light coming on occasionally when there is no drivability issues. 

Fuel economy was around 30mpg which is a bit disappointingly low tbh. My 330i auto gets better on a motorway cruise. However I can't imagine Max AC enabled for all the journey and the roof down was helping that number. Checking the fuel trims has them around the 1% mark on both banks which suggests all the Lambda sensors are behaving correctly despite the code for one.

So where did I go? 

Saturday we went to Powderham Castle classic car show near Teignmouth. Last time I went was a few years ago and it chucked it down. This time quite the opposite! Pretty good show and I'll upload all the photos later. Good mix of cars, steam, tractors and trucks.

Later then went down to Teignmouth for a walk. We did briefly drive through Torquay and intended to go for a walk, but there looked to be a massive festival on that was just starting and so bailed out of there before roads clogged up with people+cars.

 

Today we went up to Newark Park national trust as I saw there was a Bristol branch of the Austin 7 club having a show on. Being mildly* obsessed with them at the moment, I couldn't resist. Wish I could have stopped longer and watch them all drive out but Mrs SiC didn't fancy that idea when it was 28c+ blazing sun... There is limits to her patience sometimes.

Have another random car park shot to prove it did at least move off my driveway...

I'll probably upload the photos to the pre-war thread but here is an idea of how many turned up. Quite amazing really their survival rate after 86+ years since they stopped production. I wonder how long they will be still buzzing around? Given people still collect Victorian paraphernalia and even Tudor stuff is floating around, possibly for hundreds of years for a good lucky few of them? 

[SiC]

1 minute ago, cort16 said:

3 grand rack on a 4 grand car good work BMW.  A specialist would fit second hand rack they'd just not warranty the work..

Or say good luck or scrap it and gtfo of here!

[SiC]

Ahhh the warm glow of the check engine light.

It's really weird it can go for hundreds of miles and then decide suddenly to pop up. Usually on warm up too. Fuel trims are in order and the sensor is responding as it should be usually. Just sometimes it decides it's not there for a bit. Might give the connections a wiggle when it's running to see if I can get it to trigger. I'm not entirely convinced the sensor itself is at fault - more the connector or wiring.

I should also really give that dash a clean.

[SiC]

I've just realised it's been over a month since I drove this back. Nothing really to report apart from it's just being a good car now.

It's done a few hundred miles since the EML last came on and I reset it - it hasn't come back on since. I just accept it'll come on occasionally and it'll just need a reset. I'm pretty certain it's an intermittent wiring fault rather than a sensor problem. Hopefully just between the sensor and the connector to the main loom.

Otherwise it's been completely faultless and solid. It's a good case study on why sometimes you need to stick with a car for a little bit when it's being problematic, especially if you've just bought it. (That said it'll probably break on me again!)

So far I've done nearly 1k miles in it. Between 95quidpeugeot and myself, it's done over 2.5x last year's annual mileage in 2 months. Not terribly surprising that it threw up a few gremlins really.

Proof no warning lights are on!

Right now I've been using it on a regular basis whenever I've needed to go anywhere. Whether to the in-laws in Newbury or to the office today. It's comfortable, quick enough and fuel economy is being quite reasonable at ~35mpg. Certainly a fair bit better than my 330i on fuel. It also makes me ponder why I still have the 3-series. This car does everything that does except transporting 5 people - which I rarely do and have my wife's Civic. I don't think I've actually driven the 3'er for a good 3 weeks either...

No doubt my opinion will change once the honeymoon period has worn off and the newness factor. Also possibly when we hit winter. But both have heated seats and possibly this will warm up quicker having a smaller cabin? Frameless windows may become old when it starts freezing though.

Dunno but the 330i is staying for now. I probably just need to drive it and remember that having a big engined auto is a nice thing to have around. Also might have a look at the DISA valves on that and see if they're duff - that might improve it's fuel consumption a bit too. 

So do I reckon it's a good upgrade over my older Z4 E85? Actually no. That was far more fun and the less refinement made it far more characterful. I do miss that car a good bit.

However this does everything I need in a car and I don't regret the change either. I still have other cars for more driving fun. This is still a decent drive and fantastic on longer journeys - exact the reason why I bought it. 

[N Dentressangle]

Great skillz on returning it to good health. I couldn't have done it. Nice one.

[CGSB]

2 hours ago, SiC said:

So do I reckon it's a good upgrade over my older Z4 E85? Actually no. That was far more fun and the less refinement made it far more characterful. I do miss that car a good bit.

Swop ya

[JakeT]

14 hours ago, SiC said:

Frameless windows may become old when it starts freezing though.

When I've had cars with frameless windows, a good dose of sillicone spray on the rubbers stops them freezing shut in the winter, and you still get the cool looks.

 

Glad you're getting on nicely with it now though, after a bit of a fractious start.

[SiC]

Cracked out the Rubber Rejuvenator to give the seals a good going over. On a journey out earlier the roof was making a fair bit of irritating noises which cleared after briefly opening/closing the lid. Presumably because the rubber is sticking and temperature difference from it sat moves things around but not fully into a position it wants to be with the sticking rubber. 

No idea where or when I bought that. I imagine it probably was when I had my Smart Roadsters - a good 8yrs or so ago. That had stupid seals that didn't like to keep water out. 

Actually took a good half hour to go through all the seals with the top in various positions. Must be a good 20 metres worth of seals on this thing. Made more difficult from Brean beach sand in everything from our walk earlier today!

The roof did have a habit of dropping down. I think it's because it's hydraulic and the pressure drops when sat. Also it seems to hold in place for about 5 mins when the control module gives up waiting and releases all the valves making everything drop.

I keep getting low battery warnings on the dash if I leave the key in the ignition for a few minutes. It starts very readily and lively so I don't think it's actually low. Just that it needs the battery monitor resetting to think there is a new battery. However I don't want to do that unless I really know it's a new battery. So I suspect I'll need to get my wallet out and buy one. While it's fine, I rather not risk it not starting. 

[SiC]

On 23/07/2025 at 21:57, CGSB said:

Swop ya

How is the old girl getting on? Had a chance to drive it some more recently?

Not sure Mrs SiC would want to change though as she likes this new(er) one a lot right now!