It can be incredibly frustrating when your BMW key fob suddenly stops working. You might assume it’s a simple fix – just replace the battery, right? Like many BMW owners, I recently found myself in this exact situation with my i3, and what seemed like a straightforward battery swap turned into a bit of a saga, highlighting a potential quirk with BMW key fobs and battery selection.
Initially, my key fob displayed an error message, a subtle warning that the battery was getting low. Even though it was still functioning, I proactively decided to replace the battery. I grabbed a fresh, unopened Sony CR2032 battery (date code Jan 2019) – the same type specified for many key fobs. Voltage reading? A healthy 3.1 volts according to my multimeter. Confident, I swapped it in. Nothing. Tried another brand new, unopened Sony CR2032 from the same batch. Still no response from the key fob.
Concerned, I headed to my local BMW dealership in San Francisco. The service advisor presented me with a couple of options, none of them particularly appealing:
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Option 1 (Test & Possibly Replace):
- Try a BMW branded CR2032 battery ($9).
- If that failed, a $458 diagnostic fee to assess the remote.
- If the remote was indeed faulty, a further $650 for replacement, on top of the diagnostic cost.
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Option 2 (Direct Replacement):
- Try a BMW branded CR2032 battery ($9).
- Replace the remote immediately for $650.
Suddenly, a simple battery issue could potentially escalate to over $1100! The Bimmertech key fob replacement option at $485 (https://www.bimmer-tech.net/category-bmw-key-fob) started looking much more reasonable. (Note: Be sure to input your VIN on their site to see the correct key fob and pricing for your specific BMW model, as the initial picture might show a different style).
Before committing to expensive diagnostics, I decided to try the $9 BMW battery. I spoke with the parts department and asked if they frequently encountered customers in my situation – replacing a battery with a fresh aftermarket one only to have it not work. The parts specialist confirmed it was a surprisingly common issue, happening at least once a month.
And guess what? The $9 BMW battery worked! My key fob sprang back to life immediately. The original battery, despite still working initially, read 2.9 volts when removed. The first Sony battery that failed, which read 3.1 volts earlier, now measured only 2.7 volts after its failed attempt in the key fob! Even more perplexing, I later tried another Sony CR2032 from a different batch, also reading 3.0 volts, and this one inexplicably worked in the remote.
While the logic remains a bit unclear, the takeaway is: BMW key fobs can be surprisingly sensitive to battery brands. Despite seemingly adequate voltage in aftermarket batteries, they might not always function correctly. The seemingly overpriced BMW branded battery solved my problem for just $9, saving me from potentially hundreds in diagnostic and replacement costs.
So, if you’re experiencing issues with your BMW key fob even after replacing the battery, consider trying a genuine BMW battery before exploring more expensive solutions. It might just save you time, money, and a trip to the dealership. It certainly worked for me, and I’m just relieved it was a cheap and easy fix in the end, albeit a slightly illogical one!
