[newwat]

I just changed the battery on a 2017 340i xdrive from the original factory battery to an Interstate H8 AGM battery from Costco. I registered the battery with bimmerlink. The car started fine, but the fuel gauge is now showing completely empty, even though the gas is full, the back up camera doesnt work when the car is in reverse, and the left taillights are not working. Also, when I was driving it to see if the gas gauge would start working, the check engine light came on.

Any ideas on where to start for diagnoses?

[im_an_alien]

You could start by disconnecting again and reconnecting. Take off negative first and put it on last. Let it sit for a little while with the battery disconnected.

[newwat]

I tried that and the same issues are still present.

[Qsilver7]

Since you have the Bimmerlink app…do you get any errors when you scan for them? If yes, what sensors/what errors are being registered?

[newwat]

Here is what I am getting:

[LA1Z24]

Left fuel level sensor hurts the wallet. It is part of the fuel tank. To replace it, you need to replace the fuel tank. But that probably isn't the issue.

I'd check for blown fuses. Maybe the shop connected the battery terminals reversed momentarily.

[Qsilver7]

Ditto…that many errors probably was caused by an electrical glitch. Did you change the battery yourself or did you have someone else do it?

Some of the issues you mentioned like rear lights and fuel gage are clearly screaming that something occurred with the old battery/new battery swap.

If you have a large connector on top of your battery that has multiple wiring connections running from it…make sure they are all plugged in correctly. And as mentioned above, if one of the battery cables touched metal and shorted while the swap was going on, that could cause electronic glitches/issues.

You can also input your hexidecimal codes (6 digit codes) at this site. If there are multiple selections…pick the one that applies to your car (like your engine or model etc): https://bmwfault.codes/

[newwat]

I'm an idiot. I somehow unplugged this sensor when swapping the battery. Plugged back in, cleared the codes and all is good. Thanks everyone for your insight.

[im_an_alien]

All's well that ends well. Thanks for closing the loop

[cfm56d7b]

Originally Posted by im_an_alien

All's well that ends well. Thanks for closing the loop

Could not have said this any better. Wish every issue was that simple.

[TX552]

Originally Posted by newwat

I'm an idiot. I somehow unplugged this sensor when swapping the battery. Plugged back in, cleared the codes and all is good. Thanks everyone for your insight.

Good news for the OP. Shit like that will anyone insane.

[Livetodrive]

Thank goodness it was an easy fix. I’m planning on changing my battery and was worried about mysterious gremlins popping up.

[Qsilver7]

Thanks for the update…as others already mentioned…it helps the entire forum when a resolution is given. Thanks for pointing out what the culprit was…I’m sure it will help others in the future when they are changing their battery to be aware of that connection and what can happen if it remains disconnected.