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underpants

(196,529 posts) Fri Mar 6, 2026, 06:33 PM Mar 6

Need help - I changed the battery in my car key fob now it won't start with that key

2010 Honda.
This is a key fob that locks/unlocks the doors and has a panic button but I still turned the key IN the ignition to start it.

The spare key still works. Starts the car.

The key fob with the new battery unlocks and locks the car. All the lights come on but there’s nothing when I turn the key.

I’ve watched a couple videos but those mainly deal with remote start no key fobs. BTW - many of those I’ve learned do have a physical key and the way to start the car with it usually is in the glovebox.

Ideas?
Do I need to go to a dealership? 🙄💰
A locksmith?

22 replies

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Highlight:

Need help - I changed the battery in my car key fob now it won't start with that key (Original Post) underpants Mar 6 OP

Try asking at Reddit. NT mahatmakanejeeves Mar 6 #1

If you have an "automotive locksmith" in your area... LuckyCharms Mar 6 #2

Try flipping the battery. I had the same problem and i flipped the battery OLDMDDEM Mar 6 #3

This isn't a flat battery underpants Mar 6 #9

Check with a Honda forum online dweller Mar 6 #4

not editing my post dweller Mar 6 #7

I was just going to say something about that! 2naSalit Mar 6 #14

did you ever get it worked out ? dweller Mar 6 #16

I did... 2naSalit Mar 6 #17

YAY !! dweller Mar 6 #18

Take it Ace Hardware Sedona Mar 6 #5

See a locksmith that handles key fobs. Ocelot II Mar 6 #6

Thanks. I'll look it up underpants Mar 6 #12

What model Honda? nt Phoenix61 Mar 6 #8

Insight underpants Mar 6 #10

I think the Honda is the same as my Dodge van (you need a code to deal with the anti-theft system). waterwatcher123 Mar 6 #11

Yes. Great idea. I've had to do that after a battery change and, I think, a tune up underpants Mar 6 #13

This is actually pretty common these days (this is a way to keep you bringing your car to the dealer). waterwatcher123 Mar 6 #20

There's probably a reprogramming sequence... 2naSalit Mar 6 #15

Some suggestions from AI Jim__ Mar 6 #19

Thanks. underpants Mar 7 #21

Did you get this fixed? Marthe48 Mar 7 #22

mahatmakanejeeves

(69,887 posts)

1. Try asking at Reddit. NT

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:34 PM

Mar 6

LuckyCharms

(22,671 posts)

2. If you have an "automotive locksmith" in your area...

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:37 PM

Mar 6

they can typically help you out quicker than the dealer can. Good luck!

OLDMDDEM

(3,188 posts)

3. Try flipping the battery. I had the same problem and i flipped the battery

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:39 PM

Mar 6

It worked.

underpants

(196,529 posts)

9. This isn't a flat battery

Reply to OLDMDDEM (Reply #3)

Fri Mar 6, 2026, 06:48 PM

Mar 6

This is a unit that fits in the case.

dweller

(28,422 posts)

4. Check with a Honda forum online

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:40 PM

Mar 6

I seem to recall 2naSalit having a key fob issue on her non Honda vehicle , I remember finding some info for her on a forum for her car .

Something about a process of linking the key to the ignition using specific steps …

Good luck

✌🏻

dweller

(28,422 posts)

7. not editing my post

Reply to dweller (Reply #4)

Fri Mar 6, 2026, 06:44 PM

Mar 6

https://www.thehondaforums.com/

✌🏻

2naSalit

(102,843 posts)

14. I was just going to say something about that!

Reply to dweller (Reply #4)

Fri Mar 6, 2026, 07:22 PM

Mar 6

dweller

(28,422 posts)

16. did you ever get it worked out ?

Reply to 2naSalit (Reply #14)

Fri Mar 6, 2026, 07:28 PM

Mar 6

I lost track of your thread on it

✌🏻

2naSalit

(102,843 posts)

17. I did...

Reply to dweller (Reply #16)

Fri Mar 6, 2026, 07:33 PM

Mar 6

It was the reprogramming sequence that the dealer wouldn't tell me about but people here did and when I looked into it, that was the answer to the problem.

And then I sold the car to my friend who still has it and loves it.

I still have my '92 4Runner and I still love it.

dweller

(28,422 posts)

18. YAY !!

Reply to 2naSalit (Reply #17)

Fri Mar 6, 2026, 07:37 PM

Mar 6

✌🏻

Sedona

(3,872 posts)

5. Take it Ace Hardware

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:44 PM

Mar 6

They can program old keys. They did my 2012 Chevy Malibu for me

Ocelot II

(130,565 posts)

6. See a locksmith that handles key fobs.

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:44 PM

Mar 6

I lost a key fob a few months ago and found out that there's a chip in the fob that actually makes the car start. All the battery does is make it possible to unlock and lock the doors, etc., but it won't start the car. If the chip failed for some reason you'll need a new fob.

underpants

(196,529 posts)

12. Thanks. I'll look it up

Reply to Ocelot II (Reply #6)

Fri Mar 6, 2026, 07:04 PM

Mar 6

Phoenix61

(18,834 posts)

8. What model Honda? nt

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:45 PM

Mar 6

underpants

(196,529 posts)

10. Insight

Reply to Phoenix61 (Reply #8)

Fri Mar 6, 2026, 06:55 PM

Mar 6

waterwatcher123

(513 posts)

11. I think the Honda is the same as my Dodge van (you need a code to deal with the anti-theft system).

Reply to underpants (Original post)

Fri Mar 6, 2026, 06:59 PM

Mar 6

Here is the AI summary of what they recommend to unlock the anti-theft system:

"After replacing the 2010 Honda battery, the radio will likely lock, requiring a
5-digit anti-theft code entered via radio preset buttons. Locate this code on a sticker in the glove box, in the owner's manual, or online at radio-navicode.honda.com using your VIN and radio serial number.

How to Retrieve the 2010 Honda Radio Code:

Check Documents: Look for a small white card in the glove box, owner's manual, or with service records.
Online Tool: Visit https://radio-navicode.honda.com with your VIN and the serial number of your radio.
Dealer: Call a Honda dealer, provide your VIN, and they can look up the code. "

underpants

(196,529 posts)

13. Yes. Great idea. I've had to do that after a battery change and, I think, a tune up

Reply to waterwatcher123 (Reply #11)

Fri Mar 6, 2026, 07:06 PM

Mar 6

waterwatcher123

(513 posts)

20. This is actually pretty common these days (this is a way to keep you bringing your car to the dealer).

Reply to underpants (Reply #13)

Fri Mar 6, 2026, 09:38 PM

Mar 6

There are YouTube videos that walk you through the process on how to enter the code (looks pretty simple). Just do a Google search and they will turn up.

2naSalit

(102,843 posts)

15. There's probably a reprogramming sequence...

Reply to underpants (Original post)

Fri Mar 6, 2026, 07:24 PM

Mar 6

Like I found out about with my old BMW. You can just google key reprogram sequence or reprogramming ignition key for (your car) in a search and find it rather quickly if there is one and there probably is one.

Jim__

(15,224 posts)

19. Some suggestions from AI

Reply to underpants (Original post)

Fri Mar 6, 2026, 09:09 PM

Mar 6

If your 2010 Honda won't start after a key fob battery change, it is
usually due to a dislodged transponder chip, improper battery orientation, or the need for a manual re-sync.
1. Check for the Transponder Chip (Most Likely)
In many 2010 Honda keys, the small, rectangular transponder chip is a separate piece inside the fob. If it fell out or shifted when you opened the casing, the car’s immobilizer won't recognize the key, and the green key light will flash on your dashboard.

Re-open the fob and ensure the small black chip is securely in its designated slot near the base of the metal key.
Check the area where you changed the battery to see if a tiny black plastic-like piece fell out.

2. Verify Battery Installation

Orientation: Most 2010 Honda fobs (like the Accord or Insight) require the CR1616 or CR2032 battery to be placed positive (+) side down.
Contact Tabs: Ensure the small metal tabs aren't bent. They must make firm contact with the battery surface to power the chip.
Protective Film: Check if the new battery has a clear plastic film on the bottom that needs to be peeled off.

3. Perform a Manual Re-Sync
If the red light on your fob flashes when you press buttons but the car won't start, try this standard Honda Programming Sequence:

Sit in the driver’s seat with all doors closed.
Insert the key and turn it to the ON position (dash lights up).
Press the LOCK button on the fob for one second.
Turn the key to OFF.
Repeat this "ON-Press-OFF" cycle three more times. On the fourth time, the door locks should "clunk," indicating the car is in programming mode.
Press the LOCK button one last time to save the setting, then turn the key to OFF to
exit.

4. Emergency Start Tip
If the battery is just weak or poorly seated, try holding the key fob directly against the ignition switch (or Start button) while turning it. This can sometimes allow the immobilizer to read the chip even without full battery power.
These guides offer tips on replacing your Honda key fob battery and troubleshooting common starting issues:

...

underpants

(196,529 posts)

21. Thanks.

Reply to Jim__ (Reply #19)

Sat Mar 7, 2026, 08:44 AM

Mar 7

I threw the old battery and replacement casing out. I really never thought I’d need it because I just thought I was replacing a battery.

Marthe48

(23,185 posts)

22. Did you get this fixed?

Reply to underpants (Original post)

Sat Mar 7, 2026, 09:25 AM

Mar 7

We replaced battery and fobs, but it was years ago and I don't remember what we did.

Sometimes you have to go to the dealership and get it recoded. My daughter went last year, and it was fairly cheap and quick.

Hope you are all set.

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