[BMW_UK]

Hi everyone,

This morning my car flashed up with a drivetrain error and plugging in the OBD gave these codes:

21F2B1 High-Voltage Battery, Cell Module 2: Increased Charging Loss
21F2C4 High-Voltage Battery, Cell Module 2: At Least One Battery Cell In The Cell Block Is Faulty
21F257 High-Voltage Battery, Cell Block, Increased Discharge Of A Cell
21F299 High Voltage Battery, Cell Module 1: At Least One Temperature Sensor Implausible

I have been told that it will need the cell module replacing, which is £1000 plus £2000 labour. If that's what it needs then fine, but just wondered if anybody had any more information or whether it's something that not very critical? I just want to make sure I'm not being ripped off.

Many thanks,

[gavinwong]

Originally Posted by BMW_UK

Hi everyone,

This morning my car flashed up with a drivetrain error and plugging in the OBD gave these codes:

21F2B1 High-Voltage Battery, Cell Module 2: Increased Charging Loss
21F2C4 High-Voltage Battery, Cell Module 2: At Least One Battery Cell In The Cell Block Is Faulty
21F257 High-Voltage Battery, Cell Block, Increased Discharge Of A Cell
21F299 High Voltage Battery, Cell Module 1: At Least One Temperature Sensor Implausible

I have been told that it will need the cell module replacing, which is £1000 plus £2000 labour. If that's what it needs then fine, but just wondered if anybody had any more information or whether it's something that not very critical? I just want to make sure I'm not being ripped off.

Many thanks,

2020 330e here, and I had a drive train message a couple of months ago . I didn’t read the fault codes, but BMW said it was reading a cooling / heating error to the battery. They said BMW suggests to reset / update the firmware as part of several steps before getting into any physical replacement of anything battery related. Which they did, and that solved it. Still had to pay a couple hundred euros, but way better than the 000’s I was also expecting.
Are you still able to drive in electric? As my fault shut down the ability to use the electric motor / power completely.

[BMW_UK]

Thanks for the information. I was able to use the battery to drive today, but when I got home I plugged it in and it hasn't charged. I presume the car is trying to protect the battery. I guess I will have to take it to BMW, it's £250 for them just to look at it(!) Let's hope it's just a software issue!

Thanks again

[gavinwong]

Originally Posted by BMW_UK

Thanks for the information. I was able to use the battery to drive today, but when I got home I plugged it in and it hasn't charged. I presume the car is trying to protect the battery. I guess I will have to take it to BMW, it's £250 for them just to look at it(!) Let's hope it's just a software issue!

Thanks again

No worries , mine happened after I unplugged it at work so it was fully charged but with no use. And yes, some kind of limp mode to ensure things don’t get worse. I had several other symptoms btw, the thread I posted is here

https://g20.bimmerpost.com/forums/sh....php?t=2112803

Hopefully just the software for you too! I hadn’t had it updated for 3 years

[BMW_UK]

Thanks, I suspect my one is more of a physical problem than a software issue, but I will try and update the software anyway!

[Matt330e]

Hello Bimmer experts:

My first ever 2024 330e Xdrive just before delivery was diagnosed with similar issue. Dealership said that during standard inspection "vehicle exhibited multiple DTC codes in relation to overvoltage and undervoltage of the cell supervision circuits which in turn caused a cell block in cell module # 2 to fail"

They now say that they have replaced the BMS (SME) and Safety Box and reprogrammed it.

Battery Health Assessment Report: Details on the battery packs, including cell balance, state of charge, and temperature readings across the battery pack.

Cell module 1: All cell block voltages between 3.611v-3.612v, temp sensor values of all 3 sensors @ 22 C and total cell module voltage of 57.77v

Cell module 2: All cell block voltages between 3.611v-3.612v, temp sensor values of all 3 sensors @ 22 C and total cell module voltage of 54.15v

Cell module 3: All cell block voltages between 3.610v-3.612v, temp sensor values of all 3 sensors @ 22 C and total cell module voltage of 57.76v

Cell module 4: All cell block voltages betwwen 3.609v-3.611v, temp sensor values of all 3 sensors @ 22 C and total cell module voltage of 57.74v

Cell module 5: All cell block voltages between 3.609v-3.612v, temp sensor values of all 3 sensors @ 22 C and total cell module voltage of 57.74v

Cell module 6: All cell block voltages between 3.609v-3.611v. temp sensor values of all 3 sensors @ 22 C and total cell module voltage of 57.75v

Replacement cell block # 2, cell supervision circuits(6), cell supervision wiring harness and vent with cell block voltages equalised to 3.610-3.612v, temp sensors of all 3 sensors @ 22C and total cell module voltage of 57.75v

The Safety box has been replaced with the required EOS test that checks battery tightness, insulation strength, dielectric strength, cell voltage symmetrization, signal lines, functional checks of the switch contractors and a final deletion of the fault memory has been completed.

The vehicle has had a successful EOS test (End of service test) performed and programming for the replacement of the SME control unit with a successfully session required in order to put the HV battery into operation.

Now I know these are not your standard parts that are replaced and that too before delivery. Question is that what is your expert view - dealership technicians vs BMW OEM installation OR this is normal and I should carry on with the warranty etc...

Look forward to your expert views