As a Subaru owner, you probably know how important it is to maintain your vehicle. One important step in the maintenance process is ensuring the key fob still has a battery. But when the battery finally runs out, what battery size do you need?
The key fob of a Subaru Outback, and most vehicles in general, use CR2032 button cells, which are 20mm in diameter, 3.2mm in height, and have a capacity of 235 mAh. However, you can get by with CR2025 button cells, though they might not last as long.
In this guide, I’ll describe the differences between CR2032 and CR2025 button cells, as well as explain the process of replacing the battery in your Subaru Outback key fob.
CR2032 vs. CR2025
CR2032 and CR2025 are both lithium coin cell batteries. They are both commonly used as a power source for small electronic devices such as calculators, watches, and key fobs.
CR2032 batteries are slightly larger and have a higher capacity than CR2025 batteries. In fact, the 4 numbers refer to the diameter and the height of each button cell.
CR2032s measure 20 mm in diameter and 3.2 mm in height. CR2025s, on the other hand, measure 20 mm in diameter and only 2.5 mm in height. The 0.7-mm height disparity might not seem like a lot, but when you look at the technical specs, there’s a pretty significant difference.
Both CR2032 and CR2025 button cells have 3 volts, but their capacities—measured in milliampere-hours or mAh—are not similar. CR2032s have 235 mAh, whereas CR2025s only have 170 mAh. The only thing you need to know is that the higher the capacity rating, the longer it will last.
Here’s a table summary of how CR2032 and CR2025 button cells differ:
| Parameters | CR2032 | CR2025 |
| Diameter | 20 mm | 20 mm |
| Height | 3.2 mm | 2.5 mm |
| Voltage | 3V | 3V |
| Capacity | 235 mAh | 170 mAh |
Subaru Outback Key Fob Battery Size
So, in the context of Subaru Outback key fobs, what does all this mean? Very little.
The only thing you need to pay attention to when choosing a battery for your key fob is which battery size fits. Subaru Outback key fobs use CR2032 batteries—i.e., the slightly taller ones.
The good news is that either battery will fit in the key fob’s battery compartment, but you may need to add a sliver of cartonboard to make up for the missing 0.7 mm in height if you opt for a CR2025 button cell.
How to Replace the Battery in Your Subaru Outback Key Fob
Now that we know which battery to use (CR2032 or CR2025), we now have to learn how to replace the dead battery in your key fob with the new one.
Before we begin, make sure you have a flathead screwdriver and the replacement battery on hand.
Here are the steps you need to follow:
Step 1. Remove the emergency key
New Subaru Outback models will have an emergency key hidden inside the fob. To take it out, flip the key fob over and gently depress the square silver button with the screwdriver. This forces the emergency key out slightly, allowing you to remove it with your hands.
Step 2. Take the key fob apart
Insert the screwdriver on the opposite end of the metal latch that keeps the emergency key in place so as not to damage it. Now, gently twist the screwdriver 90° until the back plastic plate comes off. It should take very little effort to break it loose.
Step 3. Remove the key fob’s chip
Inside the key fob, you’ll find a green chipboard with the old button cell battery. Slowly peel the chip away from the key fob, dismantling the fob into 3 pieces (the back plate, the front plate, and the chip). While you’re at this stage, you might as well use a soft brush to remove any solid debris hidden beneath the key fob’s buttons and inside the fob.
Step 4. Remove the old battery
Pay attention to the writing on the battery. It should tell you which side is positive and which is negative. Usually, the positive terminal will face upward or away from the battery compartment.
Use the screwdriver to carefully remove the old battery from the battery compartment. You will see 2 thin plastic hooks that barely keep the battery in place. Make sure you don’t snap them!
Step 5. Insert the new battery
Again, make sure you don’t snap the 2 plastic hooks and that the battery is facing in the correct orientation. You will have to redo the whole battery replacement procedure if you place the battery in the wrong way.
Step 6. Reassemble the key fob
Now that the new battery is in place, slide the green chip board back into the top portion of the key fob and cover it with the back plate. Reinsert the emergency key until the square silver button returns to its original position.
Step 7. Test the key fob
With the key fob back together with a new battery, it’s time to test it out. Try pressing the lock and unlock buttons to make sure it’s working. If it isn’t, repeat this procedure and make sure everything is reassembled in the correct order.
If the key fob still doesn’t work, you may need to get it repaired or replaced.
How Long Do Key Fob Batteries Last?
Key fob batteries usually last for 3 years, but you can extend the battery life to up to 7 years with infrequent use. Please remember that every time you activate the remote by pressing the lock, unlock, trunk release, or alarm button, you’re using a tiny bit of the battery’s power. So, keep the key away from kids and pets and avoid getting it wet or dirty.
How to Replace Key Fob
The easiest way to replace a key fob is to go back to the Subaru dealership or an authorized mechanic. They will take you through the entire procedure of replacing and reprogramming a new key fob for you, which can take anywhere from 30 minutes to 2 hours.
You can also go to a local mechanic who has the technology to reprogram a new key fob for you. If you do, the new key fob may not come with a built-in compartment for the emergency key.
