Z4 Transmission Issues

James-Z4Lover · 07-12-2020, 06:51 PM

Hope one of the BMW Guru's on here can help me with this one...

2006 Z4 3.0Si, 65,000 miles, 2nd owner, very little issues, driven mostly only on weekends.

About a month ago, was on the highway, car was fully warmed up, started driving her a little hard, downshifted to 4th, accelerated and tried to shift up to 5th, she lagged made a slight "squeal" then finally shifted up to 5th and into 6th. Then slowed down a bit, tried again, and she stuck in 4th gear, wouldn't shift up or down, and the yellow transmission light came on.

Couldn't get her to shift at all, going into Neutral and back to D kept staying in 4th gear. So I put in Neutral, pulled off to the side, turned her off, waited about a minute, started back up, transmission light off, and she drove fine. So I drove her cautiously home w/o any further incidence.

Now, it periodically does this and seems to be getting more and more frequent. I believe it's only 4th+ gear problem, as I haven't noticed an issue w/ gears 1-3. Seems turning her off and on always resets the light and the issue, but then will happen again pretty quickly sometimes.

I've researched online and read about two potential causes:

1) Low/old transmission fluid, even though BMW says the ATF is "lifetime". Others have said this may cause shifting issues and recommend changing every 50,000 miles. I read that Valvoline Maxlife ATF is an excellent choice for the Z4 and plan to attempt that change this week. ANY TIPS here?

2) Low battery - read somewhere about potential Low Voltage may cause some electrical transmission issues. She has been starting a bit slower each time I start her over the past ~6 months but does turn over each time. New BMW battery about 2 years ago. Current Off voltage reads 12.1V, which seems low to me, thus the slow starts, but I wasn't sure if this would cause any transmission shifting issues, as I assume the alternator would provide adequate voltage was running - is that true? (I'm not at home w/ the car now, so can't test the running Voltage, but will next time I start the car).

Has anyone else experienced this and was able to solve it? With the hard shifting and "sticking" between gears, it feels like a mechanical issue to me, but being able to turn off/on the car and have it drive ok (at least for a short period of time) makes me wonder if this is an electrical problem, or a sensor, or ...?

Appreciate any help on this one, as I'm at a loss.

BTW, also ordered a OBD2 reader from Amazon recently, so can hopefully check codes soon. Although the Check Engine Light is NOT on, so not sure any codes will show up...??

Gamb1t · 07-12-2020, 07:01 PM

If your car hasn't had its tranny fluid changed, do it. You'll need to change the filter too.
Zf6hp fluid requirement is not as picky as the newer zf8.

Invest in a smart battery charger to keep cpu happy with a healthy battery. Ctek is a solid brand.

Finnegan · 07-12-2020, 07:13 PM

I wish I could offer solid pointers but I'm not familiar with the AT on these or other BMWs. All I can do is guess. You've already done some good research. Here are some ideas.

There's probably a transmission control module or two that could go bad based on how BMWs are designed, although the intermittent symptoms would seem to point elsewhere.

These cars seem to universally be very picky about voltage, and getting a full xmas tree on the dash with a bad battery is common as you already know. Have you checked the battery for loose cables or corrosion? Easy peasy to take a peek. I'd start there. Note: there's a vent tube that if not connected properly could make corrosion more likely...

I'll second the transmission fluid change. "Lifetime" sounds great, but the "lifetime" might only be 100k miles or less. Still lifetime technically no matter when the transmission life is over. Same on the CTEK battery tender--IIRC I got 10 years out of the stock AGM battery with a tender. YYMD, but they do help and pay for themselves in short order.

Let us know how things go.

Clearancediver · 07-12-2020, 07:18 PM

Given that the battery is two years old with a reading of 12.1V and it seems to be starting slower each time.... I would check voltage regulator output. You may have a failing alternator/voltage regulator leading to low voltage issue....

Finnegan · 07-12-2020, 07:25 PM

Quote:

Originally Posted by Clearancediver

Given that the battery is two years old with a reading of 12.1V and it seems to be starting slower each time.... I would check voltage regulator output. You may have a failing alternator/voltage regulator leading to low voltage issue....

Good catch!!! Agree!!!

Our03z4 · 07-12-2020, 08:13 PM

I can chime in on this one. 1st get your battery changed and make sure it's the right size and type. Also like other say, check that alternator.

Now the fun part. I've had all kinds of strange stuff go on with my 3.0si Coupe, always around 4th gear and it makes a strange horn type sound once in a blue moon, around 4k rpms, like its stuck. It also has a strange back and forth feeling under 3k rpms when it acts up. May only do it once in a few thousand miles. If you look on the UK forum other people have complained about the same issues. No matter what anyone replaces it never fixes it. I thought about dumping the car but I've decided it's still worth the occasional slip up.

It's been every where to be checked out and all say it has a clean bill of health. I've even tracked it with no increased problems. I had the transmission fluid changed, along with the rubber tubes inside for a nice cost of $900. Yep you read that right, that's what it costs. The pan is actually a single use pan in this car and the filter is built in. Didn't change a thing either. I've tried everything, well except the megatronics in the transmission, the shop said don't waste any more money.

Also thought it was the battery in the beginning but it wasn't. I figure if I get too tired of it I'll just put a 6spd in and call it a day.

Hope this isn't your issue but just warning you in case it is.

James-Z4Lover · 07-13-2020, 04:10 PM

Thanks gang. Appreciate the feedback. Received the OBD reader today and got 2 codes: 4F85 and 4F8C so I started a new thread on these topics to see if anyone has experienced these codes in the past.

Finnegan · 07-13-2020, 05:05 PM

Quote:

Originally Posted by James-Z4Lover

Thanks gang. Appreciate the feedback. Received the OBD reader today and got 2 codes: 4F85 and 4F8C so I started a new thread on these topics to see if anyone has experienced these codes in the past.

Here's a link to a fault decoder and next steps to take in the repair process. Note that both codes suggest checking fluid levels, clearing faults, and road testing. If that fails, the "fix" is replacing the transmission.

However, that's the BMW "fix" and there are other options that are less costly. Here's a thread that touches on the 4F85 and the 4F8C code. It's a good discussion with lower cost options for repair along with root causes.

If the only course available is replacing, I would examine retrofitting to a 6 speed as an option.

T-Bears · 07-28-2020, 01:56 PM

Quote:

Originally Posted by James-Z4Lover

Hope one of the BMW Guru's on here can help me with this one...

2006 Z4 3.0Si, 65,000 miles, 2nd owner, very little issues, driven mostly only on weekends.

About a month ago, was on the highway, car was fully warmed up, started driving her a little hard, downshifted to 4th, accelerated and tried to shift up to 5th, she lagged made a slight "squeal" then finally shifted up to 5th and into 6th. Then slowed down a bit, tried again, and she stuck in 4th gear, wouldn't shift up or down, and the yellow transmission light came on.

Couldn't get her to shift at all, going into Neutral and back to D kept staying in 4th gear. So I put in Neutral, pulled off to the side, turned her off, waited about a minute, started back up, transmission light off, and she drove fine. So I drove her cautiously home w/o any further incidence.

Now, it periodically does this and seems to be getting more and more frequent. I believe it's only 4th+ gear problem, as I haven't noticed an issue w/ gears 1-3. Seems turning her off and on always resets the light and the issue, but then will happen again pretty quickly sometimes.

I've researched online and read about two potential causes:

1) Low/old transmission fluid, even though BMW says the ATF is "lifetime". Others have said this may cause shifting issues and recommend changing every 50,000 miles. I read that Valvoline Maxlife ATF is an excellent choice for the Z4 and plan to attempt that change this week. ANY TIPS here?

2) Low battery - read somewhere about potential Low Voltage may cause some electrical transmission issues. She has been starting a bit slower each time I start her over the past ~6 months but does turn over each time. New BMW battery about 2 years ago. Current Off voltage reads 12.1V, which seems low to me, thus the slow starts, but I wasn't sure if this would cause any transmission shifting issues, as I assume the alternator would provide adequate voltage was running - is that true? (I'm not at home w/ the car now, so can't test the running Voltage, but will next time I start the car).

Has anyone else experienced this and was able to solve it? With the hard shifting and "sticking" between gears, it feels like a mechanical issue to me, but being able to turn off/on the car and have it drive ok (at least for a short period of time) makes me wonder if this is an electrical problem, or a sensor, or ...?

Appreciate any help on this one, as I'm at a loss.

BTW, also ordered a OBD2 reader from Amazon recently, so can hopefully check codes soon. Although the Check Engine Light is NOT on, so not sure any codes will show up...??

I would say it's a common issue with 2.5/3.0 auto transmissions or 5hp19/6hp19 auto.

For example, My Z4 2.5 auto get stuck in 3rd or 4th if I drive the car somewhat hard during summer when it's hot. I would get the yellow light and have to wait for it to cool down before I could drive it normal again. A transmission flush will improve the situation if your transmission mileage is high. However, I wanted a rebuild to freshen things up because I drive my cars hard.

I had a Tiptronic 996 Porsche a few years ago and had this issue and spent about $5700 for a full rebuild with updated parts and problem solved. Some people called it " Electrical Gremlin" on the other forum but from my experience it could just be a minor valve body, solenoid, or pulse generator replacement.

For additional info on transmission problems related to our cars here are a couple of links for both 5hp/6hp transmissions.

https://www.transmissionrepaircostguide.com/zf5hp19/

https://www.transmissionrepaircostguide.com/zf-6hp19/

BobR07Z · 07-30-2020, 05:52 PM

So I'm wondering if anybody has done a fluid change on a Z4, 6 speed, 3.0i automatic? My '07 just turned 47K miles and I'm deciding whether to service it or not and whether to use an aftermarket pan/filter? OEM pan is $336 @ dealer and only $40 aftermarket on Ebay. Big difference and all appearances seam to be the same. Anyone out there have any experience with the aftermarket item?
I've changed my top motor last month using an aftermarket motor purchased on Ebay, ($115 vs $650 OEM), with great results.
I definitely understand the mechanical reliability on the filter but $$??
Thanks for any good input....

Mantraxalos · 08-02-2020, 02:00 PM

Bobby, some friends and I just changed the fluid on an auto 06 Z4 3.0i. It should be the same GA6HP19Z trans as yours.
We bought the OEM ZF pan/filter for about $65. Maybe you were looking at the OE one with the BMW name on it.
Check some of the site sponsors and I'm sure you'll find similar pricing.
We bought 9 qts of Liqui moly 1800 ATF and about 7.5 qt were needed after the entire warmup and fill procedure.
The car shifted much smoother afterwards and it removed most of the kicking we were feeling when it was downshift into 1st or 2nd and coming to a stop.

It is stated to replace the pan bolts as they are one time use. A new drain bolt comes with the ZF filter. We reused the fill bolt.

mechatony11 · 05-18-2023, 12:17 PM

I apologize for reviving this old thread. I had a similar issue with my car, and it turned out to be having a low transmission fluid level. I did a lot of search on this issue and came on in depth article which may be worth reading, search for " BMW Transmission Problem Explained YOUCANIC" and you will see an article that goes over common causes and possible fixes
you can read about it yourself. I hope this information can assist someone else with a similar issue.

07-12-2020, 06:51 PM	#1
James-Z4Lover Registered 5 Rep 4 Posts Drives: BMW Z4 Join Date: Jul 2020 Location: Southern CA iTrader: (0)	Z4 Transmission Issues Hope one of the BMW Guru's on here can help me with this one... 2006 Z4 3.0Si, 65,000 miles, 2nd owner, very little issues, driven mostly only on weekends. About a month ago, was on the highway, car was fully warmed up, started driving her a little hard, downshifted to 4th, accelerated and tried to shift up to 5th, she lagged made a slight "squeal" then finally shifted up to 5th and into 6th. Then slowed down a bit, tried again, and she stuck in 4th gear, wouldn't shift up or down, and the yellow transmission light came on. Couldn't get her to shift at all, going into Neutral and back to D kept staying in 4th gear. So I put in Neutral, pulled off to the side, turned her off, waited about a minute, started back up, transmission light off, and she drove fine. So I drove her cautiously home w/o any further incidence. Now, it periodically does this and seems to be getting more and more frequent. I believe it's only 4th+ gear problem, as I haven't noticed an issue w/ gears 1-3. Seems turning her off and on always resets the light and the issue, but then will happen again pretty quickly sometimes. I've researched online and read about two potential causes: 1) Low/old transmission fluid, even though BMW says the ATF is "lifetime". Others have said this may cause shifting issues and recommend changing every 50,000 miles. I read that Valvoline Maxlife ATF is an excellent choice for the Z4 and plan to attempt that change this week. ANY TIPS here? 2) Low battery - read somewhere about potential Low Voltage may cause some electrical transmission issues. She has been starting a bit slower each time I start her over the past ~6 months but does turn over each time. New BMW battery about 2 years ago. Current Off voltage reads 12.1V, which seems low to me, thus the slow starts, but I wasn't sure if this would cause any transmission shifting issues, as I assume the alternator would provide adequate voltage was running - is that true? (I'm not at home w/ the car now, so can't test the running Voltage, but will next time I start the car). Has anyone else experienced this and was able to solve it? With the hard shifting and "sticking" between gears, it feels like a mechanical issue to me, but being able to turn off/on the car and have it drive ok (at least for a short period of time) makes me wonder if this is an electrical problem, or a sensor, or ...? Appreciate any help on this one, as I'm at a loss. BTW, also ordered a OBD2 reader from Amazon recently, so can hopefully check codes soon. Although the Check Engine Light is NOT on, so not sure any codes will show up...??
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07-12-2020, 07:01 PM	#2
Gamb1t Major 598 Rep 1,343 Posts Drives: 330i,X1,Z4,Solstice GXP, RX-8 Join Date: Aug 2015 Location: Canukistan iTrader: (0)	If your car hasn't had its tranny fluid changed, do it. You'll need to change the filter too. Zf6hp fluid requirement is not as picky as the newer zf8. Invest in a smart battery charger to keep cpu happy with a healthy battery. Ctek is a solid brand.
	Appreciate 1 wdb4718.00 Quote

07-12-2020, 07:13 PM	#3
Finnegan Dog Listener 701 Rep 7,850 Posts Drives: Z4M/. Z3M, E36/46 M3 Join Date: Oct 2008 Location: Teaching the dog to slalom iTrader: (22)	I wish I could offer solid pointers but I'm not familiar with the AT on these or other BMWs. All I can do is guess. You've already done some good research. Here are some ideas. There's probably a transmission control module or two that could go bad based on how BMWs are designed, although the intermittent symptoms would seem to point elsewhere. These cars seem to universally be very picky about voltage, and getting a full xmas tree on the dash with a bad battery is common as you already know. Have you checked the battery for loose cables or corrosion? Easy peasy to take a peek. I'd start there. Note: there's a vent tube that if not connected properly could make corrosion more likely... I'll second the transmission fluid change. "Lifetime" sounds great, but the "lifetime" might only be 100k miles or less. Still lifetime technically no matter when the transmission life is over. Same on the CTEK battery tender--IIRC I got 10 years out of the stock AGM battery with a tender. YYMD, but they do help and pay for themselves in short order. Let us know how things go.
	Appreciate 0 Quote

07-12-2020, 07:18 PM	#4
Clearancediver Lieutenant 90 Rep 406 Posts Drives: 2004 Z4 Join Date: Oct 2012 Location: Victoria, BC Canada iTrader: (0)	Given that the battery is two years old with a reading of 12.1V and it seems to be starting slower each time.... I would check voltage regulator output. You may have a failing alternator/voltage regulator leading to low voltage issue.... __________________ Sent from my smart phone...
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07-12-2020, 08:13 PM	#6
Our03z4 Captain 1690 Rep 685 Posts Drives: 2008 BMW Z4 3.0si Coupe, Join Date: Nov 2016 Location: USA iTrader: (0)	I can chime in on this one. 1st get your battery changed and make sure it's the right size and type. Also like other say, check that alternator. Now the fun part. I've had all kinds of strange stuff go on with my 3.0si Coupe, always around 4th gear and it makes a strange horn type sound once in a blue moon, around 4k rpms, like its stuck. It also has a strange back and forth feeling under 3k rpms when it acts up. May only do it once in a few thousand miles. If you look on the UK forum other people have complained about the same issues. No matter what anyone replaces it never fixes it. I thought about dumping the car but I've decided it's still worth the occasional slip up. It's been every where to be checked out and all say it has a clean bill of health. I've even tracked it with no increased problems. I had the transmission fluid changed, along with the rubber tubes inside for a nice cost of $900. Yep you read that right, that's what it costs. The pan is actually a single use pan in this car and the filter is built in. Didn't change a thing either. I've tried everything, well except the megatronics in the transmission, the shop said don't waste any more money. Also thought it was the battery in the beginning but it wasn't. I figure if I get too tired of it I'll just put a 6spd in and call it a day. Hope this isn't your issue but just warning you in case it is.
	Appreciate 1 wdb4718.00 Quote

07-13-2020, 04:10 PM	#7
James-Z4Lover Registered 5 Rep 4 Posts Drives: BMW Z4 Join Date: Jul 2020 Location: Southern CA iTrader: (0)	Thanks gang. Appreciate the feedback. Received the OBD reader today and got 2 codes: 4F85 and 4F8C so I started a new thread on these topics to see if anyone has experienced these codes in the past.
	Appreciate 0 Quote

07-30-2020, 05:52 PM	#10
BobR07Z New Member 19 Rep 23 Posts Drives: '07 Z4 Join Date: Jun 2020 Location: Pt. St. Lucie, FL iTrader: (0)	So I'm wondering if anybody has done a fluid change on a Z4, 6 speed, 3.0i automatic? My '07 just turned 47K miles and I'm deciding whether to service it or not and whether to use an aftermarket pan/filter? OEM pan is $336 @ dealer and only $40 aftermarket on Ebay. Big difference and all appearances seam to be the same. Anyone out there have any experience with the aftermarket item? I've changed my top motor last month using an aftermarket motor purchased on Ebay, ($115 vs $650 OEM), with great results. I definitely understand the mechanical reliability on the filter but $$?? Thanks for any good input....
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08-02-2020, 02:00 PM	#11
Mantraxalos Second Lieutenant 78 Rep 244 Posts Drives: 2006 330i Manual Join Date: Nov 2016 Location: Detroit iTrader: (0) Garage List 2007 Z4 3.0i [0.00] 2006 330I [0.00]	Bobby, some friends and I just changed the fluid on an auto 06 Z4 3.0i. It should be the same GA6HP19Z trans as yours. We bought the OEM ZF pan/filter for about $65. Maybe you were looking at the OE one with the BMW name on it. Check some of the site sponsors and I'm sure you'll find similar pricing. We bought 9 qts of Liqui moly 1800 ATF and about 7.5 qt were needed after the entire warmup and fill procedure. The car shifted much smoother afterwards and it removed most of the kicking we were feeling when it was downshift into 1st or 2nd and coming to a stop. It is stated to replace the pan bolts as they are one time use. A new drain bolt comes with the ZF filter. We reused the fill bolt.
	Appreciate 0 Quote

05-18-2023, 12:17 PM	#12
mechatony11 New Member 12 Rep 28 Posts Drives: toyota Join Date: May 2023 Location: philippines iTrader: (0)	I apologize for reviving this old thread. I had a similar issue with my car, and it turned out to be having a low transmission fluid level. I did a lot of search on this issue and came on in depth article which may be worth reading, search for " BMW Transmission Problem Explained YOUCANIC" and you will see an article that goes over common causes and possible fixes you can read about it yourself. I hope this information can assist someone else with a similar issue.
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