I fixed my BMW i3 High Voltage Problem for FREE

Hey guys and welcome back to the SimpleCarGuy channel. A few days ago, I revealed my new project car, a BMW i3 that I have purchased at an auction. The car came with no key and did not power on once I got the key from the dealer, so in this video I will go over the steps I took in order to get it started, charging and actually driving.


When I finally got the key from the dealer, I was very excited, but when I got in the car, there was no sign of any life. Of course, that was discouraging, but I knew it has been a few months since the car ran and the 12-volt battery would have died by now. I tried charging it, but it wouldn’t even be recognized by my trickle charger. I then tried connecting a portable power bank that’s powerful enough to start V8 cars and that’s the first time I heard this car make a noise inside the cabin. I didn’t want to damage any sensitive electronics and used a different method to get that 12-volt battery going. More on that in just a little bit.

Later that day, with the 12-volt battery in better condition, I was able to actually turn the ignition on! I was happy and excited, but I immediately saw error messages on the center display and dozens of codes on my scanner. That wasn’t very surprising as the car has just come back to life, so I erased all of the codes and hoped for the best! Unfortunately, the codes that remained did not leave me with high hopes, especially after doing some research.


I had the generic BMW Drivetrain Malfunction error message on the display and multiple High Voltage codes. As with many problems I run into on my cars, I don’t know how to fix them from the start, but luckily internet and manuals can be a huge help here, so I started doing some research to see what I can find. What I found had me scared as it pointed to a blown pyro fuse that’s built into the battery terminal or worse, the battery pack under the vehicle. One of the codes, 21F0CB indicated that there was a serious crash detected and thus Terminal 30C cannot be switched on and of course that meant that the high voltage battery cannot be charged or used for propulsion. It was a little bit hard to swallow that I may need to drop the battery and find someone with an EOS Tester to verify the battery integrity before I could do anything with the car. Luckily, I found some wiring diagrams that led me to understand that the High Voltage system needs to have a separate signal from the 12-volt battery, so I decided recheck all of the wires. Here is how I got my 12 volt battery to charge and what I found once I started looking under the hood.

Summary/Overview on the fix:

Looks like luck was on my side and the car was able to charge after this easy and simple fix. I definitely got lucky here and now I have a million little things to work on to make this a pleasant and fun car to drive. I’ll go give this car a quick wash and I’ll show you everything that is wrong with this car now that the high voltage system actually works. That video should be out in a few days, subscribe to the channel if you’d like to see that and let me know if you think someone tried to sabotage the car by messing with the wiring. On that note, thanks for watching and I’ll see you in the next one.