You can start a Honda with a dead key fob battery. The coin cell runs the remote buttons and the wireless range. A separate immobilizer chip in the fob talks to the car at very short range, and it does not need that coin cell. That is why a “dead” fob still starts the engine when you touch it to the start button.
The battery, stated plainly
| What this page covers | start honda with dead key fob battery |
|---|---|
| Battery to buy | Whatever the fob uses; the immobilizer does not need it to start |
| Fob you are likely holding | Push-button Honda smart key |
| Cell type | 3-volt lithium coin cell. Do not use a rechargeable LIR cell. |
| Programming after the swap | Not required when you only change the battery. |
Sit in the driver seat with your foot off the pedals for a second so you are not rushing the button. Hold the fob flat against the start button. The logo end or the end opposite the key ring is the usual spot, but if the first touch fails, turn the fob over and try the other face. Press the brake firmly, then press the start button with the fob still touching it.
The car should switch to ready or start the engine. Lock and unlock from a distance will still fail until you replace the cell. Do not keep driving for weeks on the touch method. You will eventually be outside in the rain with a fob that will not lock, and the touch trick does not help you from the parking lot.
If the touch start fails, use the mechanical emergency key hidden in the fob to open the driver door. A completely unrecognized fob, a wrong fob, or a car with a dead 12-volt battery will not start this way either. A dead car battery is the heavy battery under the hood or in the rear on some models, not the coin in your pocket. Jump-starting is a different job.
The touch point is similar on US, Canadian, European, and Australian push-button Hondas. Right-hand drive does not move the start button’s reader. Older turn-key cars do not use this ritual. You turn the metal key, and the remote battery only affects lock and unlock.
Changing the cell
Once the car is running, drive home and replace the cell the same day. Keep the emergency key in the fob afterward. People remove it and leave it in a drawer, then discover the door lock is useless the next time the cell dies in a car park.
Related guides
- Honda Key Fob Low Battery Warning
- How to Replace a Honda Key Fob Battery
- Honda Key Fob Not Working After Battery Change
- How to Open a Honda Key Fob
Questions people ask
Where do you hold a Honda key fob if the battery is dead?
Against the start button, while you press the brake and the button. Try both faces if the first try is silent.
Will this drain the car battery?
No. You are only waking the immobilizer for a start. The coin cell is what you still need to replace.
Does this work on a Honda with a turn-key ignition?
No. Turn the metal key. The fob battery on those cars is only for the remote buttons.
Honda is a trademark of Honda Motor Co., Ltd. Honda Key Fob Battery is an independent guide and is not affiliated with, endorsed by, or sponsored by Honda. The code printed on the cell already in your fob overrides any chart. A fob bought later, or a car sold in another country, can use a different shell.