Most key fob batteries take five minutes to replace and cost between $3 and $15

A dead key fob battery is one of the easiest car problems to fix yourself. The battery sits inside a plastic case that opens with a coin or flathead screwdriver, and replacement batteries are sold at any pharmacy, grocery store, or hardware retailer. The whole job takes longer to find the right battery type than to swap it out.

The challenge is knowing which battery your fob needs. Car manufacturers use different battery models across their lineup, and sometimes even different fobs for the same car model use different batteries. Your owner's manual lists the correct battery type, or you can open the fob and read the number printed on the old battery itself.

Key Takeaways

  • Key fob batteries are standard consumer batteries sold at drugstores and supermarkets, usually costing $3 to $15 for a pack of two or four.
  • The battery type is printed on the old battery itself, so you can identify the replacement without consulting your manual.
  • Opening the fob requires only a coin or flathead screwdriver and takes about one minute.
  • Dealerships charge $50 to $100 for the same five-minute job, so replacing it yourself saves money and time.

Finding the correct battery type

Before you buy a replacement, you need to know which battery your fob uses. The easiest way is to open the fob and look at the old battery. A number like CR2032, CR2025, or LR44 will be stamped or printed on the battery itself. Write down that number and take it with you to the store, or search for it online to order the replacement.

If you cannot open the fob without the battery information, check your owner's manual. Search the manual for "key fob battery" or "remote battery." The manual will list the battery type and sometimes even the part number for a replacement fob if you need one later.

Common fob batteries include CR2032 (the most frequent type), CR2025, CR2016, LR44, and LR41. A pharmacy or grocery store will have CR2032 in stock most of the time. Specialty batteries like LR41 may require a trip to an electronics retailer or an online order.

Opening the fob case

Most key fobs open along a seam that runs around the edge of the plastic case. Look for a thin line where the two halves meet. Insert a coin (a penny or dime works well) or a flathead screwdriver into that seam and gently twist. The case will pop apart, usually without any force.

Some fobs have a small button or slot on the side that you press or pry to release the case. A few luxury car fobs use a screw instead of a seam. If you see a screw, use a screwdriver that fits snugly into the head — a screwdriver that is too small will strip the screw and make it harder to open next time.

Once the case is open, you will see the battery held in a small metal clip or sitting loose in a plastic holder. Note which side of the battery faces up — the positive side (marked with a + symbol) usually faces toward you. This matters when you insert the new battery.

Removing and replacing the battery

If the battery is held by a metal clip, gently pry one end of the clip away from the battery and slide the battery out. If the battery is loose, straightforward lift it out. Set the old battery aside — you do not need it anymore, but you can recycle it at a pharmacy or electronics store if you want to.

Take your new battery and insert it with the positive side facing the same direction as the old battery faced. If the positive side faced up before, the positive side should face up now. Slide the battery under the metal clip (if there is one) or place it in the holder. The battery should sit flat and not rock or shift.

Close the fob case by pressing the two halves together. You should hear or feel a small click when the seam locks. If the case does not close smoothly, open it again and check that the battery is sitting flat and not blocking the edge of the case.

Testing the fob and troubleshooting

Press each button on the fob to test it. Stand near your car and press the lock and unlock buttons. You should see your car's lights flash or hear the locks engage. If nothing happens, the battery may not be making contact with the clips, or you may have inserted it upside down.

Open the fob again and check that the battery is sitting flat and that the positive side is facing the correct direction. If you are unsure which way is correct, try flipping the battery and testing again. Close the case and test each button once more.

If the fob still does not work after you have tried both directions, the battery may be defective (rare but possible) or the fob itself may have a problem. Try a fresh battery from a different pack or brand. If a new battery does not work, the fob may need repair or replacement, which a dealership can assess.

When to replace the battery versus the whole fob

A battery replacement costs $3 to $15 and solves the problem about 95 percent of the time. If the fob has been dropped, sat on, or exposed to water, the battery replacement may not help — the internal circuit board or buttons may be damaged. In that case, you will need a new fob.

Dealerships sell replacement fobs for $200 to $400 depending on the car model. Aftermarket fobs from online retailers cost $30 to $100 and work with most cars, though some require programming at a dealership. Before you buy a new fob, try the battery replacement first — it is cheap and usually works.

Where to buy replacement batteries

Key fob batteries are sold everywhere: drugstores like CVS and Walgreens, supermarkets, hardware stores, and online retailers. A pack of two or four CR2032 batteries costs $3 to $8. Specialty batteries like LR41 may cost slightly more or require ordering online.

You do not need to buy the battery at a dealership. Dealerships charge $50 to $100 for the same battery and labor that you can do yourself in five minutes. The battery itself is identical whether you buy it at a pharmacy or a car dealership.

Frequently Asked Questions

Can I replace the battery if I do not know what type it is?

Yes. Open the fob with a coin or screwdriver, look at the old battery, and read the number printed on it. That number is your battery type. If you cannot open the fob without knowing the type first, check your owner's manual or call your dealership and give them your car's year, make, and model.

What if the fob case will not open?

Try a different tool — a coin works better than a screwdriver for most fobs. Insert it into the seam and twist gently rather than prying hard. If the case has a screw, make sure your screwdriver fits snugly into the head. If you strip the screw, a dealership can open it, but you will pay for the service.

How long does a key fob battery last?

Most key fob batteries last three to four years with normal use. If you use the fob heavily or live in a very hot climate, the battery may drain faster. You will notice the fob working from a shorter distance before it stops working entirely.

Is it safe to replace the battery myself?

Yes. Key fob batteries are consumer-grade batteries with no special handling required. Wash your hands after handling the battery, and do not swallow it. If you have young children or pets, store old batteries out of reach until you recycle them.

What should I do with the old battery?

Most pharmacies and electronics retailers accept used batteries for recycling at no charge. You can also throw it in the trash — key fob batteries are not classified as hazardous waste — but recycling is better for the environment.