Hi all, I'm writing this to share some issues I've had with my new-to-me E89 (parasitic drain, electronic handbrake, etc), which have now been resolved. This is purely to share my experience and knowledge with other owners and prospective buyers. It's a bit of a long one so maybe get a coffee or tea ready first...
I purchased a 2010 23i in March 26, 70k miles. The car drove excellently for its age but it has had a few issues which needed resolving. Most notable of the issues was that it had a parasitic drain where leaving the car locked and unused for more than a day led to voltage drops, to a point where I would get error messages (parking brake, traction control, etc) and also struggling to start. The battery was a bit over four years old "Yuasa 5096 YBX". Previous investigation before I bought the car suggested the battery was OK, but the car drained voltage overnight - this drain was confirmed even with a different test battery. The drain issue couldn't immediately be found but advised to ensure it was locked after each use and monitored.
One day, having not driven the car for 48hrs, I had a parking brake fault on the dash. Started the engine but unfortunately the handbrake would not disable. I let the engine idle for a while but it didn't go away or allow the handbrake to disengage. I kept trying throughout the day (I.e. inadvertently charging the battery back up), but this was not fixed. Even whilst not in use and locked, the led light on the electronic handbrake button remained illuminated. Over the course of days, I got a battery charger but even at full charge the issue did not go away. The car was otherwise drivable - so this was very frustrating!!!
Useful but obvious advice #1: do not shut the boot whilst the battery is disconnected. Thank goodness BMW has jump start points under the bonnet which one can get to without needing a battery
I had heard of similar BMW parking brake problems, such as from the below video, which suggested low voltage caused a permanent fault on the parking brake which required a firmware update (spoiler, this was later found to not be the cause of the issue in my case).
Several days later I downloaded the BimmerLink app and bought the Veepeak OBD adapter - a regular OBD scanner was not sufficient to show the faults. There were a number of historic error messages across the car which is I was able to clear. However, the following four error messages related to the handbrake remained present:
- 602E Function lighting control element - Short circuit against U-Batt
- 6032 Supply voltage - Line interruption
- 604B Locking motor right Supply line - short circuit to U-Batt
- 6581 Brake status unequal
I couldn't find a great deal of detail online about these faults, but my old pal (ChatGPT) suggested these were genuine electrical faults and not clearly related to a battery drain. One other thing I noticed was that after disconnecting the battery, charging it, and reconnecting, I immediately heard what sounded like the handbrake in operation. The car still had the handbrake engaged, but I noticed the fourth error code "6581 Brake status unequal" disappeared. As soon as I then started the ignition and tried deactivating the handbrake, I heard the handbrake disengaging sound, but the car still remained with handbrake engaged (i.e. couldn't drive it). The uneven parking brake status error message then returned again! This suggested that only one side of the car had the handbrake disengaged, whilst the other remained engaged.
During this time, I noticed my engine making an unpleasant ticking sound which I had never heard before. The rate of this ticking increased with the revs, and the engine definitely didn't sound right. "What on earth is going on with this car?!" I thought ...
After doing some research, it seemed consistent with the common lifter tick issue caused by doing lots of short journeys or left idling for long period of time (I.e. my case). This wouldn't really do any harm to the engine but would require a good drive to make it go away. Regardless, I avoided starting the car again until the parking brake was fixed first and I could drive it!
A couple of weeks later, RAC came out and diagnosed water ingress into the E-box. This is where the parking brake (EMF) module sits, and you could see a puddle of water in there and corrosion/damage on the module. Fortunately all other modules, including roof module, appeared OK. I replaced this for about £150 from eBay and voila, the parking brake finally disengaged! Since then I've had no issues, bar a data timeout fault code which I'm just ignoring for now as not creating an issue.
Useful but obvious advice #2: upon reconnecting the electronic modules in the E-box, specifically the CTM roof module, please check these have been correctly fitted and no error codes BEFORE shutting the boot - or once again you may not be able to get back into it!!! Thank you ISTA.
Regarding the engine tick worry, I left this to idle for around 15 minutes. The tick remained but was slightly less audible. I then started driving, and after around 2 minutes this was no longer detectable. Thank goodness!!! Regarding the drain, it appeared to be dropping volts overnight as before, maybe slightly less, but I replaced properly with an 80Ah AGM style battery and registered to the car via BimmerCode. The battery appeared to drain much less than before, but I could still detect significant voltage drop (i.e. measuring 12.3V after 24hr, expecting 12.7-12.8V), so I didn't consider this resolved.
Then to a local BMW specialist to resolve the outstanding issues of water ingress and parasitic drain. The water ingress was apparently found to be due to a vent in the rear wing not sealing correctly. Though to be 100% sure I'm going to check the rear light fixture and seals myself as these appear to be a common cause of this leak.
Regarding the parasitic drain, this took a bit longer for diagnosis but ultimately a high resistance line was found around the positive terminal of the battery, which I believe connects to the line for pyro protection - worth replacing. The current drain during sleep was then found to reduce from 90mA to 30mA and all resolved. When I got home, I unfortunately continued to observe similar behaviour to before, i.e. measuring voltage such as 12.6V at the end of a drive, locking for 24hr and then re-measuring at 12.4V. I got a £20 battery logger (BM2) which provided live feed via Bluetooth. I was both ecstatic and frustrated to not see the voltage drop overnight... During the day... Over the following night... Etc. To confirm my latest theory, I unlocked the car and bam, 0.2 - 0.3V drop immediately. Upon relocking the car and leaving for over an hour to sleep, back to the previous voltage.
Overall, I think we can call this a happy ending on what felt at one point like a neverending cascade of issues. This is a significant peace of mind now, in preparation for our road trip to Cornwall in September. I'll spend a bit of time in the background observing the water ingress (or hopefully lack of), focussing on the rear right taillight seals and potentially filling the third unused fixing hole. See below video for more info:
Hope this has been helpful! And happy to report that otherwise the car has been a total pleasure and hopefully will continue to be for many years.
I purchased a 2010 23i in March 26, 70k miles. The car drove excellently for its age but it has had a few issues which needed resolving. Most notable of the issues was that it had a parasitic drain where leaving the car locked and unused for more than a day led to voltage drops, to a point where I would get error messages (parking brake, traction control, etc) and also struggling to start. The battery was a bit over four years old "Yuasa 5096 YBX". Previous investigation before I bought the car suggested the battery was OK, but the car drained voltage overnight - this drain was confirmed even with a different test battery. The drain issue couldn't immediately be found but advised to ensure it was locked after each use and monitored.
One day, having not driven the car for 48hrs, I had a parking brake fault on the dash. Started the engine but unfortunately the handbrake would not disable. I let the engine idle for a while but it didn't go away or allow the handbrake to disengage. I kept trying throughout the day (I.e. inadvertently charging the battery back up), but this was not fixed. Even whilst not in use and locked, the led light on the electronic handbrake button remained illuminated. Over the course of days, I got a battery charger but even at full charge the issue did not go away. The car was otherwise drivable - so this was very frustrating!!!
Useful but obvious advice #1: do not shut the boot whilst the battery is disconnected. Thank goodness BMW has jump start points under the bonnet which one can get to without needing a battery
I had heard of similar BMW parking brake problems, such as from the below video, which suggested low voltage caused a permanent fault on the parking brake which required a firmware update (spoiler, this was later found to not be the cause of the issue in my case).
Several days later I downloaded the BimmerLink app and bought the Veepeak OBD adapter - a regular OBD scanner was not sufficient to show the faults. There were a number of historic error messages across the car which is I was able to clear. However, the following four error messages related to the handbrake remained present:
- 602E Function lighting control element - Short circuit against U-Batt
- 6032 Supply voltage - Line interruption
- 604B Locking motor right Supply line - short circuit to U-Batt
- 6581 Brake status unequal
I couldn't find a great deal of detail online about these faults, but my old pal (ChatGPT) suggested these were genuine electrical faults and not clearly related to a battery drain. One other thing I noticed was that after disconnecting the battery, charging it, and reconnecting, I immediately heard what sounded like the handbrake in operation. The car still had the handbrake engaged, but I noticed the fourth error code "6581 Brake status unequal" disappeared. As soon as I then started the ignition and tried deactivating the handbrake, I heard the handbrake disengaging sound, but the car still remained with handbrake engaged (i.e. couldn't drive it). The uneven parking brake status error message then returned again! This suggested that only one side of the car had the handbrake disengaged, whilst the other remained engaged.
During this time, I noticed my engine making an unpleasant ticking sound which I had never heard before. The rate of this ticking increased with the revs, and the engine definitely didn't sound right. "What on earth is going on with this car?!" I thought ...
After doing some research, it seemed consistent with the common lifter tick issue caused by doing lots of short journeys or left idling for long period of time (I.e. my case). This wouldn't really do any harm to the engine but would require a good drive to make it go away. Regardless, I avoided starting the car again until the parking brake was fixed first and I could drive it!
A couple of weeks later, RAC came out and diagnosed water ingress into the E-box. This is where the parking brake (EMF) module sits, and you could see a puddle of water in there and corrosion/damage on the module. Fortunately all other modules, including roof module, appeared OK. I replaced this for about £150 from eBay and voila, the parking brake finally disengaged! Since then I've had no issues, bar a data timeout fault code which I'm just ignoring for now as not creating an issue.
Useful but obvious advice #2: upon reconnecting the electronic modules in the E-box, specifically the CTM roof module, please check these have been correctly fitted and no error codes BEFORE shutting the boot - or once again you may not be able to get back into it!!! Thank you ISTA.
Regarding the engine tick worry, I left this to idle for around 15 minutes. The tick remained but was slightly less audible. I then started driving, and after around 2 minutes this was no longer detectable. Thank goodness!!! Regarding the drain, it appeared to be dropping volts overnight as before, maybe slightly less, but I replaced properly with an 80Ah AGM style battery and registered to the car via BimmerCode. The battery appeared to drain much less than before, but I could still detect significant voltage drop (i.e. measuring 12.3V after 24hr, expecting 12.7-12.8V), so I didn't consider this resolved.
Then to a local BMW specialist to resolve the outstanding issues of water ingress and parasitic drain. The water ingress was apparently found to be due to a vent in the rear wing not sealing correctly. Though to be 100% sure I'm going to check the rear light fixture and seals myself as these appear to be a common cause of this leak.
Regarding the parasitic drain, this took a bit longer for diagnosis but ultimately a high resistance line was found around the positive terminal of the battery, which I believe connects to the line for pyro protection - worth replacing. The current drain during sleep was then found to reduce from 90mA to 30mA and all resolved. When I got home, I unfortunately continued to observe similar behaviour to before, i.e. measuring voltage such as 12.6V at the end of a drive, locking for 24hr and then re-measuring at 12.4V. I got a £20 battery logger (BM2) which provided live feed via Bluetooth. I was both ecstatic and frustrated to not see the voltage drop overnight... During the day... Over the following night... Etc. To confirm my latest theory, I unlocked the car and bam, 0.2 - 0.3V drop immediately. Upon relocking the car and leaving for over an hour to sleep, back to the previous voltage.
Overall, I think we can call this a happy ending on what felt at one point like a neverending cascade of issues. This is a significant peace of mind now, in preparation for our road trip to Cornwall in September. I'll spend a bit of time in the background observing the water ingress (or hopefully lack of), focussing on the rear right taillight seals and potentially filling the third unused fixing hole. See below video for more info:
Hope this has been helpful! And happy to report that otherwise the car has been a total pleasure and hopefully will continue to be for many years.
E89: Collection of the typical age-related defects in the roof environment
North West Surrey
Scottish Borders