During a freezing morning last winter, I pressed the start button on my 2019 BMW 530e and… nothing. The dashboard screamed “No key detected” even though the fob was right in my pocket. Turns out the battery inside the key had died overnight. Ten minutes and one tiny coin battery later, the car fired right up. If your 5 Series (G30/G31 or even the newer G60) is ignoring your key or the little yellow light is flashing, this exact thing is probably happening to you right now.
Key Takeaways: Grab a CR2450 battery for Display Key models or CR2032 for regular diamond-shaped keys, pop the hidden metal key out from the bottom, slide the back cover toward the keyring end, gently pry the case open with a plastic tool, swap the battery positive-side up, snap everything closed, and hold the fob against the steering column to wake the car up if it still complains.
Spotting Exactly Which 5 Series Key You Have
BMW loves confusing everyone with key designs. Your 5 Series from 2017–2023 (G30) usually came with the big “Display Key” that has a touchscreen and shows range, climate, and lock status. Newer 2024+ G60 models switched back to the slimmer diamond-style key without the screen. Open your key – if you see a color display inside, you need a CR2450 battery. No screen? It’s the common CR2032 everyone sells in checkout lanes.
Knowing this matters because putting the wrong battery in will either rattle around or not make contact. I once helped a friend who jammed a CR2032 into his Display Key and the car kept thinking the key was dead. Switched to the thicker CR2450 and it worked instantly.
Quick check: press the silver button on the back – if a metal key pops out and the fob feels chunky with a glass-like front, you have the Display Key.
- Display Key (2017–2023) → CR2450
- Regular Comfort Access key (2024+ G60 or older replacements) → CR2032
- Never force the wrong size – it kills contact points
Tools You Actually Need (and What Not to Use)
You don’t need a toolbox. Seriously – most people do this with stuff already in the house. Best tool: a plastic pry tool from a phone repair kit or even the edge of a credit card. If you only have a small flat screwdriver, wrap the tip in electrical tape so you don’t scratch the soft-touch plastic.
Skip metal guitar picks or knives – one slip and you’ll have permanent scars on a $300 key. I keep a cheap $5 iFixit plastic spudger in the glovebox just for this.
Also grab the new battery before you start. Gas stations overcharge like crazy ($12 for a single coin cell). Buy a two-pack of name-brand Energizer or Panasonic on Amazon for six bucks and keep the spare in the car.
- Plastic pry tool or taped flat screwdriver
- Correct battery ready in your hand
- Soft cloth to set the circuit board on (no carpet static)
Opening the Key Without Breaking Anything
Flip the key over. Push the small chrome slider at the bottom and pull the metal emergency key completely out – it only comes out one way. Now look at the spot where the metal key was. You’ll see a tiny notch.
Slide the empty back cover toward the keyring end (the fat part with the hole). It moves about 5 mm and stops. That’s normal. Now wedge your plastic tool into the seam right above where the metal key sat and gently twist. The back pops off super easy – don’t force it like a stubborn pickle jar.
Inside you’ll see either the big touchscreen board (Display Key) or the simple circuit on regular keys. Everything is held by tiny clips, not glue, so nothing breaks if you’re gentle.
- Slide cover, not pry yet
- Use the notch, not random seams
- Pop sound = success, not destruction
Swapping the Battery the Right Way Every Time
Look at the old battery – the writing and + symbol always face up toward you. Pull it straight out with your fingernail or the plastic tool. The Display Key has a thicker CR2450 that sits in a round holder; regular keys have the thinner CR2032 sitting loose under two tiny springs.
Drop the new battery in exactly the same orientation – positive side (the side with writing) facing you. If it’s upside down the key will be completely dead even with a fresh battery. I see this mistake constantly.
Give the battery a gentle press so it seats flat. If you have the Display Key, the screen usually lights up the second contact is made – instant gratification.
- + writing faces YOU
- Press until it clicks flat
- Screen lights = you nailed it
Putting It All Back Together and Testing
Place the back cover on at a slight angle and slide it away from the keyring end until it clicks flush. Slide the metal emergency key back in until it locks – you’ll feel it.
Now walk to the car. If the key was completely dead, the car might still say “no key detected.” Just hold the BMW roundel logo on the back of the key directly against the steering column (right side where the key symbol is etched) for five seconds while pressing start. The car reads the chip through RF and starts right up. Do this once and the new battery registers forever.
Lock and unlock the doors a few times from 20 feet away – if everything works smoothly, you’re golden.
- Slide cover opposite direction from opening
- Emergency key locks the cover in place
- Touch steering column trick saves tow trucks
When It Still Doesn’t Work (Rare Fixes)
About once every hundred keys, the car needs a quick re-sync. Sit in the driver seat, close the door, hold the key against the steering column again, and press start without touching the brake. Wait ten seconds. Now press the brake and start normally. This forces the immobilizer to re-learn the key.
If the little yellow key light stays solid on the dash, your key might need professional coding (super rare for just a battery swap). Any BMW dealer does it in ten minutes for about $100.
- Re-sync trick fixes 99 % of “still dead” complaints
- Solid yellow light = possible deeper issue
- Spare key still works? Then it’s definitely the fob
Final Thoughts
Changing the battery in your BMW 5 Series key takes literally three minutes once you’ve done it once, costs under ten bucks, and saves you a dealership trip that would easily run $150–$200. Keep a spare battery and plastic tool in the center console and you’ll never stand in the rain wondering why your $80,000 car won’t start again. Do it today before it dies at the worst possible moment – you’ll thank yourself later.
| Action | Exact Detail / Tool | Pro Tip |
|---|---|---|
| Identify key type | Look for touchscreen inside | Wrong battery = no start |
| Remove metal key | Push chrome slider, pull straight out | This unlocks the back cover |
| Slide back cover | Toward keyring end ~5 mm | Creates gap to pry |
| Pry case open | Plastic tool in emergency key slot | Tape any metal tool |
| Remove old battery | Lift straight up | Check orientation before tossing |
| Insert new battery | + side (writing) facing you | Press flat until flush |
| Reassemble | Slide cover opposite way, insert metal key | Must click fully |
| Wake car if needed | Hold logo against steering column 5 seconds | Works even with completely dead battery |
Frequently Asked Questions (FAQs)
Is it the same process for the 2024 G60 5 Series key?
Yes, almost identical, but the new G60 keys are slimmer and use the CR2032 battery every single time – no more Display Key option. The back still slides the exact same way and you pop it open in the emergency key slot. The whole job feels even easier because the case is lighter.
Can I use cheap dollar-store batteries?
You can, but I’ve had them die in three months instead of the normal 2–3 years. Name-brand Energizer, Duracell, or Panasonic last way longer and actually put out the full 3 volts the key expects. Spend the extra dollar – it’s still cheaper than one Starbucks.
Do I need to reprogram the key after changing the battery?
99.9 % of the time, no. The chip that starts the car never loses its coding. Only the low-power radio part dies when the battery is flat. Once you put the new battery in and touch the steering column once, everything works exactly like before.
Is it safe to pry with a small screwdriver?
Only if you wrap the tip in electrical tape or painter’s tape first. The soft-touch coating scratches crazy easy and you can’t un-scratch it. Plastic phone tools cost three bucks online and never leave a mark.
Can the key get water damaged while open?
Yes – don’t do this in the rain. The circuit board hates water. If you drop it in a puddle while open, dry everything with a hair dryer on cool before closing. I’ve saved three keys this way.
Do I need two batteries for the Display Key?
No, just one CR2450. Some older Mercedes keys used two CR2025s stacked, but BMW uses a single thicker CR2450. Never stack batteries – you’ll crack the screen.
Is the battery different for iDrive 8 cars?
No change at all. Whether you have iDrive 7 or the newest iDrive 8.5, the physical key hardware stayed identical for battery swaps.
Can I replace the battery preventively every year?
Totally smart move. I swap mine every Christmas no matter what. Takes three minutes while the turkey is in the oven and I never get stranded again.
