Acura Key Fob Battery Replacement: CR2032 Smart Keys, CR1616 Older Keys, and How to Open Each
Every Acura smart key with push-button start, from the 2013 ILX and RDX to the current MDX, TLX and Integra, takes one CR2032 battery. The older keys with a metal blade, the 2007 to 2014 flip keys and the separate remotes before them, take a thinner CR1616. To open a smart key, slide the release, pull out the emergency key, and twist a flat tool in the slot it came from. Fit the new cell the same way round as the old one. No reprogramming is needed.
Acura uses the same key hardware as Honda, which means two battery sizes across the range. Mix them up and the key will not work: a CR2032 is too big for a flip key, and a CR1616 rattles around in a smart key holder. The second thing people get wrong is where to pry. Acura smart keys open from the slot the emergency key sits in, not from the outside seam. This guide tells you which battery your key takes, shows where each type opens, and covers what to do if the car still does not see the key afterwards.
Which battery your Acura key fob takes
The battery depends on the style of key, not the model. Find your key in the table, then confirm the code against the old battery once the case is open. The FCC ID printed on the back of the fob tells you which family it belongs to.
| Key style | Typical FCC ID | Common on | Battery |
|---|---|---|---|
| Separate remote on the key ring | OUCG8D-387H-A, OUCG8D-439H-A, E4EG8DJ | TL 2004 to 2008, TSX 2004 to 2008, RL 2005 to 2012 (non smart-key), MDX 2001 to 2006, RSX, Integra 1998 to 2001 | CR1616 |
| Flip key (blade folds into the remote) | N5F0602A1A, MLBHLIK-1T | MDX 2007 to 2013, RDX 2007 to 2012, TL 2009 to 2014, TSX 2009 to 2014, ZDX, ILX 2013 to 2015 (base) | CR1616 |
| Smart key, 2013 to 2020 style | KR5V1X, KR5V2X, M3N5WY8145, ACJ932HK1210A | RDX 2013 to 2018, MDX 2014 to 2020, TLX 2015 to 2020, ILX 2016 to 2022, RLX, TL and RL with keyless access | CR2032 |
| Smart key, current style | KR5T21, KR5V21, KR5TP-4, KR5TP-2 | RDX 2019 on, TLX 2021 on, MDX 2022 on, Integra 2023 on, ZDX 2024 on | CR2032 |
The code stamped on the flat + face of the old battery is the final word. A CR1616 is 16 mm across and only 1.6 mm thick, so it looks like a coin shaved thin; a CR2032 is 20 mm across and twice as thick. If the old battery is missing, the owner’s manual lists the type in the section on the keyless remote or smart entry system.
The code tells you the size: the first two digits are the diameter in millimetres and the last two are the thickness in tenths of a millimetre. That is why a CR2032 will not drop into a CR1616 holder, and why a CR2025 in a CR2032 holder sits loose and makes patchy contact. Our key fob battery size chart lists every size by brand.
What you need
- One new battery of the exact code printed on the old one (Panasonic, Energizer, Duracell, Murata or Acura branded all work)
- A small flat-blade screwdriver, a coin, or a plastic pry tool
- A clean table and good light, so a dropped battery or the small rubber button pad does not vanish
Avoid rechargeable cells such as LIR2032. They have the right shape but a higher voltage, and they are not what the key is designed for. A branded 3 V lithium cell with a date well into the future is all you need.
Changing the battery in an Acura smart key
This covers every push-button start Acura from 2013 on. The older rounded key and the current squared-off key open the same way.
Slide the small catch on the back of the fob and pull the metal key blade straight out. Put it somewhere safe; you may use its tip in the next step.
Look into the opening the key blade came from. There is a small notch between the two halves. Push the tip of a flat screwdriver or the key blade into that notch and twist gently. The back cover lifts off. Do not pry around the outside seam; that is how cases get chewed up.
Before you touch the battery, look at which side shows. On Acura smart keys the + side with the code printed on it normally faces the back cover, but take a photo so there is no guessing later.
Use a plastic tool or the tip of the emergency key at the small cut-out beside the battery to lever it up, and lift it out by the edge. Do not slide a metal tool across the circuit board.
Hold the new cell by its edges and press it into the holder the same way round as the old one. It should sit flat and click under the retaining tab. A battery that rocks or stands proud is the wrong size.
Snap the cover back on, slide the emergency key home until it clicks, and press lock and unlock. The lights should flash and the small LED on the fob should blink with each press.
If the rubber button pad came away with the cover, lay it back in the front half first, buttons facing out, before you close the case. A pinched pad is why buttons feel mushy after a battery change, and why the remote start or trunk button sometimes stops working.
Changing the battery in an Acura flip key or remote
The 2007 to 2014 flip key and the older separate remotes both take a thin CR1616.
- On the flip key, press the button to fold the blade out. There is a small Phillips screw on the back of the remote half; remove it, then split the case at the notch on the edge. On the separate remotes there is no screw: find the notch on the seam and twist a coin in it.
- Work the two halves apart slowly rather than forcing one spot.
- Note which way the battery faces, then lever it out from the cut-out at its edge. On most Acura flip keys the + side faces down, towards the circuit board, so check before you remove it.
- Press in the new CR1616 the same way round, check the rubber button pad is seated, snap the halves together until the seam is flush all the way round, and refit the screw.
The transponder chip that lets the car start is sealed in the key head and does not use the battery. So even with a completely dead remote the key still turns the ignition and starts the engine; you just have to unlock the door by hand.
3V lithium coin cell in the size printed on your old battery
Acura smart keys take a CR2032; flip keys and older remotes take a CR1616. Buy a name brand in a small multi-pack and keep the spares in the glove box, not loose in the fob.
Other size: CR1616
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Do you need to reprogram an Acura key after a battery change?
No. The pairing between the key and the car is stored in memory that does not depend on the battery, so an Acura key keeps working as soon as a fresh cell goes in. If the dash showed a Keyless Remote Battery Low message, it clears after the next start or two. If the car still shows it after a day of normal driving, the new cell is probably the wrong size or from a tired pack.
If the car still does not see the key
First, get moving. If a push-button Acura shows Keyless Remote Not Detected or the Start button light does not come on, hold the back of the fob directly against the Engine Start/Stop button. You will hear a beep, which means the car has read the chip in the key through the button. Press the brake and push the button within about ten seconds. The emergency key blade opens the driver’s door if the remote lock does not respond; on newer models the lock cylinder is under a small cap on the handle that pops off with the key tip.
Then work through the usual causes, in order of how often they turn out to be the problem:
- Wrong size. A CR2025 or CR2016 in a CR2032 holder makes patchy contact and the key works one day and not the next. Compare the code on the new cell with the old one.
- Upside down. If the key does nothing at all and the LED does not flash, open it and turn the battery over.
- Bent or dirty contact. The spring contact can be flattened by prying. Lift it gently with a plastic tool and clean it with a dry cotton bud. See how to clean key fob battery contacts.
- Tired new battery. Cells that sat in a drawer or came from an unbranded multi-pack can be flat out of the packet. Try a second one from a fresh pack.
- The car’s 12 V battery. If the car was also slow to crank or the dash lights were dim, the problem is the car, not the key. See can a bad car battery cause key fob problems.
- Damage inside the key. A fob that has been dropped hard, through a wash, or left on a hot dashboard can have a cracked solder joint or corroded board. A locksmith can test whether it still transmits.
Acura keys share their electronics with Honda, so the fixes in Honda keyless remote not working apply. The general checklist is in key fob not working after a battery replacement.
What it costs
An Acura dealer parts counter will usually fit a battery while you wait for the cost of the cell plus a small labour charge, and some do it free during a service. The larger figures only apply if the key itself has to be replaced. Acura smart keys are at the higher end because the dealer has to order the key against the VIN and program it to the car, so it is worth keeping a working spare.
How long the new battery will last
A flip key or separate remote only transmits when you press a button, so a CR1616 in one typically lasts two to four years. The push-button smart key listens for the car and answers whenever you touch a door handle, so expect one to two years from a CR2032, less if the key lives within a few feet of the car overnight. Cold weather, a key carried loose with things that press the buttons, and heavy use of remote start all shorten that. More detail is in 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 dispose of old batteries at a drop-off point rather than in 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
Acura smart keys with push-button start take a CR2032. The older flip keys and separate remotes take a thinner CR1616. Confirm with the code printed on the old battery.
Slide the catch and pull out the emergency key, then push a small flat screwdriver or the tip of the key blade into the notch inside the slot it came from and twist. The back cover lifts off. Do not pry at the outside seam.
No. Acura keys keep their pairing without battery power. The key works as soon as the new battery is in, and the low battery message clears after the next start or two.
Hold the back of the fob directly against the Engine Start/Stop button until you hear a beep, then press the brake and push the button within about ten seconds. The button reads the chip in the key. Use the emergency key blade to unlock the driver’s door.
No. The flip key holder is made for a 16 mm CR1616 and a 20 mm CR2032 will not fit. The other way round, a CR1616 in a smart key is far too small to make contact. Use the exact size the key was designed for.
The car usually needs a start cycle or a short drive to update. If it stays on, check that the new cell is a CR2032 from a fresh pack, the right way up, and that the spring contact in the key is not flattened.