Sometimes you’re rushing out the door, hit the unlock button on your Lexus ES350 key fob, and nothing happens. Dead silence. You press harder, shake it like it owes you money, and suddenly realize – the battery inside is completely toast. That tiny coin cell has been powering your luxury life for years, and now it’s time to give it a quick swap before you’re stuck in the parking lot looking silly.
The great news? Changing the battery in a Lexus ES350 key fob (2007–2024 models) is stupidly easy, costs under $5, and takes less than five minutes – even if you’ve never touched a tool in your life. Let’s fix it right now.
Key Takeaways: Grab a CR1632 battery and a small flat tool (plastic pry tool is safest). Press the silver button to pop out the metal key, flip the fob over, and gently pry open the back cover from the small notch. Lift out the old battery with your fingernail, drop in the new one with the + side facing down, snap the cover back on, slide the metal key in, and test the buttons. Done – your key works like new instantly.
Spotting the Signs Your Key Battery Is Dying
Your Lexus ES350 is smart – it actually warns you before the key battery dies completely. The first clue shows up on your dashboard as “Key Battery Low” when you start the car. Ignore that message for a week or two and the range gets shorter – you’ll be standing two feet from the car mashing the button. Then one day the doors won’t unlock at all unless you use the metal key hidden inside.
Another sneaky sign is when the red LED on the fob flashes weakly or not at all when you press a button. Most people panic and run to the dealer thinking the whole fob is broken, but 99% of the time it’s just that $3 battery. I’ve seen friends pay $150 for a “diagnosis” when all they needed was a trip to the drugstore.
The battery usually lasts 2–4 years depending on how often you click the buttons. If you have two keys and one suddenly feels sluggish while the other is snappy, that’s the clearest proof – same car, same usage, different battery life.
- Dashboard shows “Key Battery Low” message
- Unlock/lock range drops dramatically
- Red LED on fob is dim or doesn’t light
- You hear a very faint click instead of strong beep from the car
Tools You Actually Need (and What Not to Use)
You only need two things: a fresh CR1632 battery (not CR2032 – that’s too thick) and something flat to pry with. The safest choice is a plastic pry tool – the kind that comes in phone repair kits for $5 on Amazon. A taped flathead screwdriver works in a pinch, but plastic won’t scratch your $300 key fob.
Never use a naked metal screwdriver or knife – one slip and you’ll have an ugly gouge on the chrome. I wrap the tip of a small screwdriver with two layers of electrical tape when I’m in a hurry, and it’s never failed me. Also keep a clean finger or paper towel ready so you don’t get skin oil all over the circuit board inside.
While you’re at the store, grab two batteries. Throw the spare in your glovebox so you’re never stuck again. Trust me, the day your key dies will be pouring rain at night far from home.
- Plastic pry tool (best) or taped flathead screwdriver
- CR1632 lithium battery (double-check the number!)
- Spare battery for the glovebox
- Clean finger or tissue to handle the new battery
Releasing the Hidden Metal Emergency Key
Every Lexus ES350 smart key has a metal key blade hiding inside for emergencies. Start by flipping the fob over so the Lexus logo is face down. Look at the skinny end – you’ll see a small silver button. Push it firmly with your thumb and the metal key slides right out with a satisfying click.
Don’t yank super hard – it’s designed to come out smooth. Once it’s out, set the metal key on the table so you don’t lose it. That empty slot is actually the perfect spot to grip when you pry the case open later.
Some people forget to remove the metal key first and end up fighting the case forever. Doing it this way makes the next part ten times easier and prevents you from bending anything inside.
- Flip fob logo-side down
- Press silver release button firmly
- Slide metal key completely out
- Set metal key safely aside
Opening the Key Fob Without Breaking It
With the metal key removed, look at the same end where the key came out – there’s a tiny notch. Slip your plastic pry tool (or taped screwdriver) into that notch and gently twist. You’ll hear a soft click as the back cover pops loose. Work your way around the seam if it feels stuck, but never force it hard.
The two halves are held by small plastic clips, not glue, so they separate easily when you pry in the right spot. Once the back lifts a little, use your fingers to pull it the rest of the way. Inside you’ll see a green circuit board and the round silver battery sitting in its holder.
Take a second to notice how the rubber buttons line up with the board – this helps when you put it back together. If any dust or crumbs are inside, blow them out gently.
- Insert tool into notch at metal-key end
- Twist gently to pop first clip
- Work around the edge slowly
- Lift back cover completely off
Removing the Old Battery and Inserting the New One
The battery sits in a round holder with a tiny clip on one side. Use your fingernail or the plastic tool to push that clip toward the center – the old battery pops right up. Lift it out and check the number to confirm it says CR1632.
Grab your new battery (touch only the edges) and drop it in with the + side facing down – you’ll see the + symbol through the clear plastic on the bottom. It only fits one way, so don’t force it. Push until it clicks flat.
Wipe the contacts with a dry cloth if they look dirty – that prevents future issues. The whole swap takes literally ten seconds once you’ve done it the first time.
- Push small clip to release old battery
- Confirm old battery says CR1632
- Insert new battery + side down
- Press until it clicks flush
Closing Everything Up and Testing
Place the back cover on at a slight angle and press around the edges until you hear clicks all the way around. Slide the metal key back in until the silver button clicks – that locks everything tight. Now walk to your car and test every button from 20–30 feet away.
Your doors should lock and unlock instantly, trunk should pop, and the red LED on the fob should flash bright. Start the car with the key in your pocket to confirm full strength. If something still feels weak, you probably got a bad battery – swap the spare and you’re golden.
That’s it – you just saved yourself a dealer trip and feel like a total boss.
- Snap cover closed firmly all around
- Reinsert metal key fully
- Test all buttons from normal distance
- Start car to confirm perfect range
Final Thoughts
Changing the Lexus ES350 key fob battery is one of those tiny jobs that feels amazing when you do it yourself. Five minutes, three bucks, and zero stress next time you’re late for work. Keep a spare CR1632 in the center console and you’ll never get locked out again. Do it once and you’ll laugh at how simple it really is – go try it right now!
| Step | What to Do | Pro Tip |
|---|---|---|
| 1. Spot low battery | Watch for “Key Battery Low” message or weak range | Replace as soon as you see the warning |
| 2. Gather tools | Plastic pry tool + CR1632 battery | Buy two batteries – keep one as spare |
| 3. Remove metal key | Press silver button and slide key out | Do this first – makes prying way easier |
| 4. Open the case | Pry gently in the notch at key end | Use plastic tool to avoid scratches |
| 5. Swap battery | Pop out old, insert new + side down | Only touch battery by the edges |
| 6. Reassemble | Snap cover, reinsert metal key | Press edges until you hear clicks |
| 7. Test everything | Lock/unlock from 30 feet + start car | Weak still? Try your spare battery |
| 8. Celebrate | You just saved $100+ | Teach a friend – they’ll be amazed |
Frequently Asked Questions (FAQs)
Is it safe to change the Lexus ES350 key battery myself?
Absolutely yes – thousands of owners do it every day without any issues. The key fob is designed to open easily, and there’s no programming needed when you just replace the battery. As long as you use the right CR1632 and don’t force anything, you cannot damage the key. I’ve done it on my 2018 ES350 over five times with zero problems.
Can I use a CR2032 instead of CR1632?
No, never – a CR2032 is thicker and will either not fit or push against the circuit board and cause weird issues. Some people force it in and the buttons stop working properly. Stick to the exact CR1632 (it’s only a dollar more) and your key will work perfectly for years.
Do I need to reprogram the key after changing the battery?
Not at all for the ES350. As long as you only swap the battery and don’t damage the chip, the car recognizes the key instantly. I’ve changed batteries in parking lots and driven off immediately – no trip to the dealer required.
Is it okay to use a metal screwdriver to open the fob?
Only if you wrap the tip with electrical tape first. Bare metal can scratch the chrome or slip and nick the circuit board. Plastic pry tools are five bucks and make the job scratch-free every time.
Can the key still start the car when the battery is dead?
Yes! That’s why Lexus hides the metal key inside – you can manually unlock the driver door and start the car by holding the fob right against the push-start button. The car reads the chip through induction even with a completely dead battery.
Do I have to replace both key fobs at the same time?
Nope – replace them whenever the low battery message appears for each one. They usually die months apart. Just keep spare CR1632 batteries in the glovebox and you’re always ready.
Is the battery direction important?
Very much – the + side must face down toward the circuit board. If you install it backward, the key won’t work at all and you’ll think something is broken. Look for the tiny + symbol and match it to the old battery.
Can I get the battery at any store?
Yes – CR1632 is super common. You’ll find them at Walmart, CVS, AutoZone, even the grocery store checkout. Just double-check the package says CR1632, not 1620 or 2032.
