REx fault and HV error codes

I have a late 2013 REx which is showing more and more faults. Does anyone have experience of these please?
1. on top of the frequent "Drivetrain Error - possible to continue journey" I have frequently after RExing for >30 mins, I had a new one yesterday which said REx was unavailable and to go to nearest dealer.

I didn't want BMW to charge £400 to investigate for a few hours so I continued driving. The "REx unavailable" error has cleared, but I still have the Drivetrain error which won't clear despite turning on and off.

2. I just got the car diagnosed by a non-BMW dealer in my local village who came up with the following errors which won't clear:

21FO64: HV electrical system isolation resistance below fault threshold value
22280F: HV electrical system isolation resistance below warning threshold

He managed to clear a number of other electrical errors.

Does anyone have any experience of the above please?

Losing confidence in the car...

Thanks

A failing 12vdc battery can lead to some weird faults. Has yours been replaced? The procedure is a bit different to do that than in a typical ICE...you should isolate the HV system before removing the 12vdc battery, and don't try to use an external battery charger on it unless it's removed, IOW, don't try to do it in the car.

Thank you. I will contact bmw ans see what they say. The reality is that many dealers don’t have a clue about the hundreds of complex faults that i3s can develop. Where is the 12v battery? How do you shut down the Jb system completely and then restart it?

sjjhr said:

Where is the 12v battery? How do you shut down the Jb system completely and then restart it?

Click to expand...

This is the official procedure for replacing the 12 V battery. Follow the link on the referenced page to learn how to deactivate the high-voltage system.

The 12vdc battery is in the front of the vehicle...you can access it from the frunk after removing some pop off panels, and the storage box, if you're going to replace it.