BMW Key Fob Battery Replacement: Which Battery (CR2032, CR2450, or Rechargeable) and How to Change It
It depends on the generation. BMW keys from about 2010 on (F-series and G-series) have a user-replaceable coin cell under a slide-off cover: a CR2032 on most 1, 2, 3 and 4 Series, X1, X2 and all 2017-and-newer G-series keys, and a CR2450 on many 2010 to 2016 5, 6 and 7 Series, X3, X4, X5 and X6 keys. Older E-series keys (roughly 2002 to 2012) and the Display Key have a rechargeable cell that charges in the car and is not meant to be replaced. Read the code on the old battery. To change it, press the release, pull out the emergency key, slide the small cover off the back, swap the cell the same way round and slide the cover back. No reprogramming is needed.
BMW keys divide into two camps: the ones with a battery you can change in a minute, and the older ones with a sealed rechargeable cell that only charges while the key sits in the ignition slot. Knowing which you have saves a wasted trip to the shop. This guide tells you which battery each BMW key takes, how to open the slide cover without marking the key, what to do about a rechargeable key that no longer holds a charge, and what to check if a new battery does not bring the key back.
Which battery your BMW key takes
| Key style | Generation | Common on | Battery |
|---|---|---|---|
| Diamond-shaped and slot-type keys (key goes into a dash slot) | E-series, about 2002 to 2013 | 3 Series E46 and E90, 5 Series E60, 1 Series E8x, X3 E83, X5 E53 and E70, Z4, 6 and 7 Series of the period, MINI R56 and R60 | Rechargeable (VL2020), not user-replaceable |
| Key with slide-off battery cover, smaller body | F-series, about 2011 to 2019 | 1 Series F20, 2 Series F22, 3 Series F30, 4 Series F32, X1 F48, X2, M2, M3 F80, M4, i3, i8, MINI F56 2014 on | CR2032 |
| Key with slide-off battery cover, larger body | F-series, about 2010 to 2017 | 5 Series F10, 6 Series F12, 7 Series F01, X3 F25, X4 F26, X5 F15, X6 F16, 5 GT | CR2450 (some CR2032; read the code) |
| Current key with slide-off cover | G-series, 2017 on | 5 Series G30, 3 Series G20, 7 Series G11 and G70, X3 G01, X5 G05, X7, 8 Series, Z4 G29, 4 Series G22, i4, iX, 2 Series G42 | CR2032 |
| Display Key (small screen on the key) | Optional on G-series | 7 Series, 5 Series, X5, X7 and others | Rechargeable, charged by USB or wireless pad |
The F-series split is the one to watch: the 3 Series key and the 5 Series key of the same year take different cells. If your key has a slide cover, open it and read the code on the flat + face of the old battery before you buy. If it has no slide cover and no visible seam, it is a rechargeable key.
The CR2450 is 24.5 mm across and 5 mm thick; the CR2032 is 20 mm and 3.2 mm. Neither fits the other’s holder. Our key fob battery size chart covers every common size.
What you need
- One new CR2032 or CR2450 to match the old cell. Panasonic, Varta, Energizer, Duracell or Murata; BMW dealers sell the same cells
- A small flat-blade screwdriver or a plastic pry tool
- A clean surface with good light
Skip rechargeable LIR cells in a key that takes a CR cell. They have the same shape but a higher voltage than the key is built for.
Changing the battery in an F-series or G-series BMW key
Press the small release button on the back of the fob, near the key ring end, and pull the metal key blade out.
With the blade out, you can see the end of a small cover on the back of the key. Put the tip of the key blade or a flat screwdriver into the slot where the blade came out and push the cover towards the far end. It slides a few millimetres and lifts off. There is no need to split the whole key.
On BMW keys the + side with the code faces up towards you under the cover. Take a photo before you touch it.
Lever it up at the cut-out beside it with the key tip or a plastic tool and lift it out by the edge.
Hold it by the edge and press it in the same way round. It should sit flat without rocking; a cell that rattles is the wrong size.
Slide the cover back on until it clicks, push the emergency key home, and press lock and unlock. The LED flashes with each press when the battery is good.
If you have a rechargeable E-series key
These keys contain a small rechargeable VL2020 cell soldered to the board. It charges whenever the key sits in the ignition slot with the engine running, so a key that is driven regularly can last a decade. The problems come with a spare key left in a drawer, or a Comfort Access car where the key is never put in the slot. Signs of a flat rechargeable cell are a remote that only works right next to the car, or a Comfort Access key that stops unlocking by touch.
Your options, in order of cost:
- Charge it. Put the key in the ignition slot and drive for an hour or two, or leave the car running in a safe place for 30 minutes. Repeat over a few days. A cell that has only run down, rather than failed, usually comes back.
- Have the cell replaced. The key is glued shut, but an independent key specialist or a careful DIYer can open it, desolder the old VL2020 and solder in a new one with tabs. Budget about $50 to $120 at a specialist. Replacement cells with tabs cost a few dollars.
- Replace the key. A new key from BMW, cut and coded to the car, is typically $300 to $600 or more and takes a week or two to arrive.
Whatever its battery state, the transponder chip in an E-series key still starts the car when the key is pushed into the slot, because the slot powers it. You only lose the remote buttons and Comfort Access until the cell is charged or replaced.
CR2032 3V lithium coin battery (most BMW keys 2011 on)
Most F-series 3 Series-type keys and every G-series key take a CR2032. The larger F-series 5, 7 and X5-type keys take a CR2450; see the link below. Buy a name brand and check the date on the pack.
Larger F-series keys: CR2450
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Do you need to reprogram a BMW key after a battery change?
No. The pairing is stored in memory that does not need battery power, so the key works as soon as the new cell is in. If iDrive showed Remote control battery low or a key symbol with a battery, the warning clears after the next start or two. Programming is only needed for a key that is new to the car, and on a BMW that is done by the dealer or a specialist with the car’s VIN.
If the car still does not see the key
First, start the car. On a push-button BMW, hold the key against the steering column, just below the Start button on most models, with the buttons facing the column; the car reads the chip through a backup antenna there. Keep it there, press the brake and push Start. The owner’s manual shows the exact spot under Starting with a discharged key battery. On slot-type E-series cars, push the key into the slot as usual. The emergency key blade opens the driver’s door; the lock cylinder is under a small cap on the handle that pops off with the blade.
Then check, in this order:
- Battery size. A CR2032 in a CR2450 key rattles and makes patchy contact. Compare the new code with the old one.
- Battery upside down. No LED flash at all usually means the cell is reversed.
- Flattened contact. The spring contact can be pressed down while prying. Lift it gently with a plastic tool and wipe it with a dry cotton bud. See how to clean key fob battery contacts.
- A flat new battery. Unbranded multi-pack cells and cells that have sat for years can be dead in the packet. Try one from a fresh, dated pack.
- The car’s 12 V battery. If the car was also slow to crank or threw other warnings, the key is not the problem. See can a bad car battery cause key fob problems.
- Damage inside the key. A key that has been dropped hard, through the wash or left on a hot dash can have a cracked solder joint. A specialist can test whether it still transmits before you pay for a new key.
The full checklist is in BMW key fob not working and key fob not working after a battery replacement.
What it costs
Many BMW dealers will fit a coin cell free or for the price of the cell during a service visit. The larger figures only apply when the key itself has to be replaced.
How long the new battery will last
A BMW key with Comfort Access listens for the car and answers whenever you touch a handle, so expect one to two years from a CR2032 and two to three from the larger CR2450. Without Comfort Access, three years or more is typical. Cold winters, keeping the key within a metre or so of the car overnight, and carrying it loose where items press the buttons all shorten that. See how long key fob batteries last.
Safety: keep coin batteries away from children and pets
A swallowed coin cell can cause serious internal burns within hours. Keep spares and the old cell out of reach, and take old batteries to a drop-off point rather than household waste. If you think a child has swallowed a battery, go to the emergency room straight away and call the National Battery Ingestion Hotline at 1-800-498-8666, or Poison Help at 1-800-222-1222.
Frequently Asked Questions
Keys from about 2011 on take a CR2032 (most 1, 2, 3 and 4 Series, X1, and all 2017-and-newer G-series keys) or a CR2450 (many 2010 to 2016 5, 6 and 7 Series, X3, X4, X5 and X6 keys). Older E-series keys and the Display Key have a rechargeable cell. Confirm with the code on the old battery.
Press the release on the back and pull out the emergency key, then push the small battery cover towards the far end with the key tip. It slides off; there is no need to split the key.
It has a rechargeable cell that charges in the ignition slot. Drive with the key in the slot to recharge it. If it no longer holds a charge, a key specialist can resolder a new VL2020 cell, or the dealer can supply a new key.
No. BMW keys keep their pairing without battery power. The key works as soon as the new battery is in, and the low battery warning clears after the next start or two.
Hold the key against the marked spot on the steering column, just below the Start button on most models, press the brake and push Start. Use the emergency key blade to open the driver’s door.
No. The CR2450 is wider and thicker, so a CR2032 rattles in its holder and loses contact. Use the code the key was designed for.