How to Reprogram Key Fob After Battery Replacement

For the last twenty years, keyless entry systems have become a common feature in numerous vehicles. Generally, the wireless remotes, commonly referred to as fobs, have remained quite unchanged. These fobs contain a microchip powered by a tiny battery, which sends out an accurate frequency to a control unit. This control unit can subsequently unlock the doors, open the trunk, activate the panic alarm, or even ignite the engine. Depending on storage conditions and the frequency of use, key fob batteries typically last between 1 to 5 years.

Usually, when a key fob’s battery is depleted, it can be replaced, allowing the fob to function normally again, though sometimes reprogramming of the fob is necessary. Stay tuned as we explore the signs of a dying fob battery, how to test it, instructions for changing the key fob battery, and how to reprogram key fob after a battery replacement.

Why Does Replacing a Battery Influence Key Fob Performance? 

Unlike other circuit boards found in computer modules, radios, display units, and amplifiers, key fob microchips lack capacitors. Capacitors function to store electrical energy, similar to batteries. Upon removing the battery from the key fob, its ‘memory’ or programming may be compromised. If the key fob ceases to operate after a battery change, a reprogramming process might be necessary.

Indicators of a Failing Key Fob Battery

Common signs that the battery is either depleted or has low voltage include:

• The key fob fails to unlock the door locks entirely.
• The key fob sporadically unlocks the door locks.
• The trunk release feature is inoperative.
• The remote ignition fails to function.
• The emergency button is nonfunctional.

How To Evaluate A Key Fob Battery

If you believe the battery in your key fob needs changing, you can assess it. Similar to a car battery, this involves taking out the battery from the fob following the steps outlined below and testing it using a multimeter. Key fob batteries, like the CR2032 or CR1616, should register around 3V. Should the key fob battery read below 2.7V, it will fail to function properly. Our guide on gauging a car battery with a multimeter offers additional details on how to utilize this tool.

How To Change A Key Fob Battery

• Replacing the battery in a key fob is an easy process that requires only basic tools, and on some vehicles, it can even be done without any tools whatsoever. Here are the steps to change a key fob battery:
• Find the cutout slot on the fob. This is utilized to split the key fob halves apart.
• Using a flat-head screwdriver, a key, your fingernail, or a plastic knife, gently pry the fob halves apart.
• Take careful note of how the battery is oriented and what type of battery is in use. Some key fobs have indications that show the correct orientation of the battery, while others may not.
• Lift the key fob battery out by prying it upward.
• Insert the appropriate replacement battery into the key fob. (The type of battery will be marked on the battery itself)
• Verify the orientation or direction of the battery once more.
• Align the fob halves and press them together; you should hear a ‘click’ sound.
• Press the buttons on the key fob; the key fob shouldhttps://wheelsrush.com/car-idles-fine-but-sputters-when-accelerating/ light up a red indicator (if applicable).
• Your key fob should now be operational. If it’s not functioning correctly, you might need to reprogram it.

Also Read: Car Idle Fine But Sputters When Accelerating

How to Reprogram Key Fob

• Place the key into the ignition cylinder and turn the cylinder to the ‘ON’ position.
• Press and maintain the ‘Lock’ button on the key fob for around 1–2 seconds.
• Switch the key to the ‘OFF’ position and pause for 1–2 seconds.
• Rotate the key to the ‘ON’ position again, and pause for 1–2 seconds.
• Press and hold the ‘Lock’ button once more for an additional 1–2 seconds.
• Rotate the ignition key to the ‘OFF’ setting.
• This procedure must be carried out four times. During the fourth cycle, the doors will become locked. This verifies that the key fob has been successfully programmed.
• Verify the operation by pressing both the ‘Lock’ and ‘Unlock’ buttons while observing the functioning of the door lock. If the locks fail to lock and unlock properly, the fob hasn’t been set up

Battery Types

Below is a list of key fob battery types from several major automakers.