So, you thought replacing the battery in your BMW key fob would be a simple fix? You grabbed a fresh, unopened CR2032 battery, maybe even checked the voltage to confirm it was around 3V, and… nothing. Frustration sets in. You’re not alone in this surprisingly common BMW key fob dilemma.
Like many BMW owners, I recently faced this exact situation. Armed with a brand-new Sony CR2032 battery, confidently reading 3.1 volts on my multimeter, my BMW key fob remained stubbornly unresponsive. Thinking it might be a fluke, I tried another fresh battery – still no luck. This led me down the path to a BMW dealership appointment and a potentially expensive diagnostic adventure.
My service advisor at BMW San Francisco presented me with a couple of options, none of them particularly appealing to my wallet:
Option 1 (The “Maybe” Route):
- Try a BMW branded CR2032 battery ($9.00).
- If that fails, a $458 diagnostic to assess the remote.
- If the diagnostic points to a faulty remote, replacement at $650 plus the diagnostic cost.
Option 2 (The “Let’s Just Replace It” Route):
- Try a BMW branded CR2032 battery ($9.00).
- Replace the remote outright for $650.
Suddenly, a simple battery replacement was looking at a potential cost of $1100 versus a “cheaper” $660 option. At this point, the Bimmertech key fob replacement option at $485 (https://www.bimmer-tech.net/category-bmw-key-fob) started to seem significantly more attractive. (Note: Make sure to enter your VIN on their site to see the correct key fob and pricing for your specific BMW model, as the initial pictures might be misleading).
Out of curiosity and a bit of desperation, I decided to invest the $9 in a BMW-branded CR2032 battery. During my visit to the parts department, I asked a question that many of you might be wondering: “How often do customers come in with the same issue – new, fresh battery replacement failing to work?” The parts specialist’s answer was surprisingly frequent – “at least once a month.”
And guess what? The $9 BMW battery worked! My key fob sprang back to life. Initially, I had received a key fob error message on my dashboard (I unfortunately don’t recall the exact wording), but the fob was still functioning. I proactively decided to change the battery. The original battery, even though reading 2.9 volts, was still operational. Two brand new, unopened Sony batteries, reading 3.1V and 3.0V respectively, failed to power the key fob. The BMW battery, however, did the trick.
Intrigued, I re-checked the first “dead” Sony battery that initially read 3.1v when I left home. Now, it was reading 2.7v! While I’m not a battery engineer, this voltage drop is perplexing. However, another Sony battery, initially reading 3.0v on my digital multimeter, did work in the remote after all – further adding to the confusion.
The logic behind why some new batteries fail while BMW-branded ones succeed remains a bit of a mystery. Perhaps there’s a subtle difference in the internal resistance, discharge curve, or some other characteristic that BMW key fobs are particularly sensitive to.
The good news is that I avoided expensive diagnostics and a costly key fob replacement, resolving the issue for just $9 and a bit of my time. The lesson learned? When it comes to BMW key fob battery replacement, it might be worth starting with a BMW-branded battery, even if it seems a bit overpriced. It could save you time, frustration, and a potentially hefty bill.
Have you experienced similar issues with your BMW key fob battery replacement? Share your feedback and experiences in the comments below!
