Multiple codes after 12v battery change

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New member
Mar 25, 2023
I have a 2014 I3 REX with about 31,000 miles on it. The 12v battery died and prior to that I had an engine warning light which BMW read and reported crankshaft sensor error. A cool $3400+ repair as they have to pull the REX to replace it.
So I took it to BMW to replace and recode the new battery. $700. After they replaced the battery they are reporting multiple error codes and have BMW NA involved?
I want to sell the vehicle to CarMax as I am tired of dealing with it. The electric range is poor 67 miles and the Rex sounds like an angry lawnmower when it runs. Not surprising for 650 cc BMW motorcycle engine.
Any thoughts or similar experiences?
When an i3's 12 V battery fails such that its voltage drops to below a certain limit, all sorts of spurious error codes are stored. If the replacement battery isn't charged before installing it and its voltage is below a certain limit, more error codes could be stored.

Your BMW dealer might not have erased these error codes which could prevent an i3 from operating correctly. Or maybe they didn't charge the replacement battery before installing it. Either would be a really stupid mistake, especially considering how much they charged for the battery replacement. Of course, I have no idea what they did, so maybe there's a real problem that hasn't been resolved.

A fix other i3 owners have performed is to fully charge the replacement battery before erasing the error codes with an OBD scanner. Even then, some have reported that their i3's had to sit overnight before their i3's began operating correctly.

Good luck!