G20 330e 21F1C8

Daveyvtec · 07-27-2025, 05:05 PM

Hi all, quick question. My 2020 330e threw a spanner light in the dash. I scanned it with BimmerLink and got the code 21F1C8 which BimmerLink tells me is HVS: Cell Monitoring, cell defect detected in module 6.

I had been driving for a while, a couple of hundred kilometers and used the onboard charger a couple of times during the day. Now the car won’t charge. BimmerLink will clear the code after a few tries but the light stays on the dash and still no charging.

Anyone familiar with this issue? I’m seeing some places saying it needs a software/firmware update, other saying a whole battery replacement! Any bit of guidance will do here. Thanks

phiber · 10-05-2025, 09:12 AM

Check out this video:

If it's not the module itself then it's the BMS of that module.
You'll need to get this fixed.

07-27-2025, 05:05 PM	#1
Daveyvtec Enlisted Member 41 Rep 37 Posts Drives: BMW F30 318 M Sport Join Date: Nov 2021 Location: Limerick, Ireland iTrader: (0)	G20 330e 21F1C8 Hi all, quick question. My 2020 330e threw a spanner light in the dash. I scanned it with BimmerLink and got the code 21F1C8 which BimmerLink tells me is HVS: Cell Monitoring, cell defect detected in module 6. I had been driving for a while, a couple of hundred kilometers and used the onboard charger a couple of times during the day. Now the car won’t charge. BimmerLink will clear the code after a few tries but the light stays on the dash and still no charging. Anyone familiar with this issue? I’m seeing some places saying it needs a software/firmware update, other saying a whole battery replacement! Any bit of guidance will do here. Thanks Attached Images
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10-05-2025, 09:12 AM	#2
phiber Registered 0 Rep 3 Posts Drives: BMW 330e G21 Join Date: Sep 2025 Location: Croatia iTrader: (0)	Check out this video: If it's not the module itself then it's the BMS of that module. You'll need to get this fixed.
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