You can replace the battery yourself in about two minutes with a coin
The Acura MDX key fob uses a CR2032 coin cell battery that you can swap out without tools or a trip to the dealer. The fob splits open along a seam on the side, the battery slides out, and a new one slides in. The whole job takes longer to find a CR2032 than to do it.
You will need a coin — a dime or penny works — and a replacement CR2032 battery from any drugstore, supermarket, or hardware store. They cost between $3 and $8 for a single battery, or $5 to $15 for a pack of two or three. Keep a spare on hand because the battery will die again in two to four years depending on how often you use the fob.
Key Takeaways
- The MDX key fob opens by sliding a coin into the seam on the side and twisting gently to pry the two halves apart.
- The CR2032 battery sits in a small metal holder and lifts straight out; note which side faces up before you remove it.
- A new CR2032 costs $3 to $8 at any pharmacy or grocery store and takes two to four years before it needs replacing again.
- If the fob still does not work after you install a fresh battery, the problem is likely a worn contact or a dead circuit board, not the battery itself.
Step-by-step: opening the fob and removing the old battery
Look at the side edge of your key fob for a small seam that runs around the perimeter. This is where the two plastic halves meet. Insert a coin — a dime or penny — into the seam at the point where it is widest, usually near the bottom or side of the fob.
Turn the coin slowly, as if you are opening a jar lid. The plastic will flex slightly and the two halves will begin to separate. Do not force it; if you meet hard resistance, try a different spot along the seam. Once the halves are loose enough, you can pry them apart by hand. Set the metal battery holder and circuit board aside on a clean surface so you do not lose the small spring that may be attached to it.
The CR2032 battery sits in a shallow metal cup. Note which side is facing up — the flat side or the domed side — because the new battery must go in the same way. Lift the battery straight out. If it is stuck, a gentle nudge with your fingernail will free it.
Installing the new battery and closing the fob
Take your new CR2032 battery and place it into the metal holder with the same side facing up as the old one. The battery should sit flat and level in the cup. Press it down gently until you hear or feel a small click; this means it is seated correctly.
Align the two halves of the fob so the seam lines up evenly all the way around. Press them together firmly until they snap into place. You should hear a distinct click when the two halves lock. Test the fob by pressing each button — the lock, unlock, and panic buttons should all respond when ready. If nothing happens, open the fob again and check that the battery is seated correctly and facing the right direction.
What to do if the new battery does not fix the problem
If you installed a fresh CR2032 and the fob still does not work, the battery was not the issue. The problem is usually a worn metal contact inside the fob or a failed circuit board. These parts are not user-replaceable.
Your options are to buy a replacement fob from a dealer — which costs $150 to $400 depending on the year of your MDX — or to have a locksmith reprogram an aftermarket fob, which typically costs $50 to $150. Some locksmiths can also repair worn contacts if you bring the fob in, though this is less common. Before you spend money on either route, confirm that the battery is actually new and installed correctly by testing it in another device that uses CR2032 batteries, such as a watch or calculator.
Where to buy CR2032 batteries and how to avoid running out
CR2032 batteries are sold at every pharmacy, grocery store, and hardware store in the country. Walgreens, CVS, Walmart, Target, and Home Depot all stock them in the battery aisle. Online retailers like Amazon also carry them, though you will pay shipping unless you have a membership.
Buy a pack of two or three batteries instead of a single one. The cost difference is small — usually $2 to $4 more for a pack — and you will have a spare when the first one dies. Store the extra battery in a cool, dry place. Do not leave it in a hot car or a humid bathroom, as heat and moisture shorten battery life.
Why your MDX key fob battery dies and how to make it last longer
The CR2032 battery in your fob drains slowly over time even when you are not using it. Most people get two to four years of normal use before the battery is too weak to operate the fob reliably. If you use your fob very frequently — pressing the buttons many times per day — the battery may last only 18 months. If you use it rarely, it may last four years or longer.
You cannot extend the battery life much, but you can avoid draining it faster by not pressing the buttons unnecessarily. Avoid leaving the fob in direct sunlight or in a hot car, as heat accelerates battery drain. If you will not be using your MDX for several weeks, remove the battery from the fob to prevent it from draining completely.
Frequently Asked Questions
Can I use a different battery size instead of CR2032?
No. The CR2032 is the only battery that fits the Acura MDX key fob. Other sizes will not fit in the metal holder, and using the wrong battery can damage the circuit board. Always buy a CR2032 specifically.
What does CR2032 mean?
CR stands for lithium coin cell. The 2032 refers to the physical size: 20 millimeters in diameter and 3.2 millimeters thick. This size is standard across most manufacturers, so a CR2032 from any brand will work in your fob.
Do I need to reprogram the fob after I change the battery?
No. Changing the battery does not erase the fob's programming. Once you install the new battery and close the fob, it will work when ready without any additional steps.
What if I lose one of the plastic halves when I open the fob?
Contact an Acura dealer or a locksmith who carries MDX fob parts. They can sell you a replacement housing. Bringing in the circuit board and metal battery holder will help them match the correct replacement.
Is it safe to touch the battery with my bare hands?
Yes. CR2032 batteries are safe to handle with bare hands. They produce no heat and carry no risk of shock. Wash your hands afterward if you prefer, but it is not necessary.