How to Fix a Keyless Entry System That Won't Work

What to do when your keyless entry stops working

A keyless entry system that fails usually points to one of three problems: a dead battery in the fob, a broken receiver in the car, or a damaged fob itself. Most of the time, you can fix it without a trip to the dealer. Start by replacing the battery in your fob — a CR2032 or similar coin cell costs a few dollars and solves the problem in roughly half of all cases. If that does not work, try the spare fob if you have one. If the spare works, your original fob is damaged. If neither fob works, the receiver in your car needs attention.

The cost to repair ranges from $10 for a battery to $300 or more for a new receiver module, depending on what has failed and whether you do the work yourself or take it to a dealer. A locksmith or independent mechanic often charges less than a dealership for the same repair.

Key Takeaways

• Replace the battery in your fob first — it is the cheapest fix and works most of the time.
• Test your spare fob to narrow down whether the problem is in the fob itself or in the car's receiver.
• A locksmith or independent shop usually costs less than a dealership for fob and receiver repairs.
• Some cars let you reprogram a fob yourself using a sequence of key turns and button presses — check your owner's manual for the steps.
• If your car is under warranty, the dealer may cover receiver repairs at no cost.

How to replace the battery in your fob

Most fobs use a coin-cell battery, usually CR2032, CR2025, or CR2016. Look up your fob model online or check your owner's manual to find the exact type. Buy a replacement at any pharmacy, grocery store, or hardware store for $3 to $8.

Open the fob by prying gently at the seam with a flathead screwdriver or coin. Some fobs have a small slot or button that releases the case. Once open, note which side of the battery faces up — the positive side is usually marked with a + symbol. Remove the old battery and slide the new one in the same direction. Close the fob and test it on your car. If the fob still does not work after a fresh battery, move on to testing your spare.

Testing your spare fob to find the real problem

If you have a second fob, use it to unlock your car. This step tells you whether the problem lives in the fob you were using or in the car itself. If the spare fob works perfectly, your original fob is broken and needs replacement. If the spare fob also fails, the receiver module in your car is the issue.

Keep in mind that a spare fob may not have been used in months or years, so its battery might also be dead. Replace the battery in the spare fob before you test it. If both fobs fail even with fresh batteries, the car's receiver is almost certainly the culprit.

When to replace the fob versus the receiver

A damaged fob costs $150 to $400 to replace at a dealership, though independent locksmiths often charge $75 to $200. Some fobs can be repaired if only a button or circuit contact is damaged, which may cost less than a full replacement. A receiver module failure is more expensive — typically $200 to $500 at a dealership, or $150 to $350 at an independent shop — because it requires removing interior panels and reprogramming.

Before you pay for a new receiver, ask the shop whether your car's receiver can be tested without removal. Some shops can diagnose a dead receiver with a scan tool before you commit to the repair. If your car is still under the manufacturer's warranty, contact the dealership first, as receiver repairs are often covered.

Reprogramming a fob yourself

Many cars allow you to reprogram a fob without visiting a dealer. The process varies by make and model — some use a sequence of key turns in the ignition, others use button combinations on the fob itself. Check your owner's manual for the exact steps, or search online for "[your car year, make, model] fob programming."

If your car supports self-programming, the process usually takes five to ten minutes and costs nothing. If it does not work, or if your manual does not list programming instructions, you will need a dealer or locksmith to reprogram the fob using specialized equipment. A locksmith typically charges $50 to $150 for reprogramming, compared to $100 to $250 at a dealership.

Choosing between a dealer, locksmith, and independent mechanic

A dealership has access to your car's exact specifications and can order genuine parts, but charges the highest labor rates. An independent locksmith often specializes in fobs and receivers and charges less, though not all locksmiths work on every car brand. An independent mechanic can handle receiver repairs but may need to order the part and may not stock fobs for your specific model.

Call ahead and ask for a quote before you commit. Mention your car's year, make, and model, and describe the symptom — whether only the fob is not working or whether the spare fob also fails. A shop that asks these questions is more likely to give you an accurate price and to solve the problem on the first visit.

What to do if your car is recalled for keyless entry problems

Some cars have been recalled for keyless entry defects — for example, fobs that fail prematurely or receivers that stop responding. Check the National Highway Traffic Safety Administration (NHTSA) website and search for your vehicle by year, make, and model. If a recall exists for your keyless system, the dealership must repair or replace the faulty part at no cost, even if your warranty has expired.

To find recalls, visit safercar.gov, enter your vehicle information, and look for any recall notices related to keyless entry or remote keyless systems. If a recall applies to your car, contact your dealership and reference the recall number. The repair is free and usually takes an hour or less.

Frequently Asked Questions

How long does a fob battery last?

A fob battery typically lasts three to four years with normal use, though this varies based on how often you press the buttons. If you use your fob multiple times per day, the battery may last only two years. Batteries in spare fobs that sit unused can last longer.

Can I use any coin-cell battery in my fob?

No — use only the battery type specified for your fob model. Using the wrong size or chemistry can damage the fob's circuit board or cause it to malfunction. Check your owner's manual or the fob's battery compartment for the correct type, usually printed on the case.

What if my fob gets wet?

Remove the battery immediately and let the fob dry completely for 24 to 48 hours in a warm, dry place. Do not try to use it while wet. After it dries, replace the battery with a fresh one and test it. If water damage has corroded the circuit board, the fob will need replacement.

Can a dead car battery cause keyless entry to stop working?

Yes — if your car's battery is very low or dead, the receiver module may not have enough power to respond to the fob. Charge or replace your car battery first, then test the fob. If the fob works after the car battery is restored, the fob and receiver are fine.

Is it worth repairing an old fob or should I replace it?

If the fob is simply out of battery or needs reprogramming, repair is worth it. If the fob is physically damaged or the circuit board is corroded, replacement is usually cheaper than repair. Ask a locksmith or dealer for a repair estimate before you decide — if repair costs more than 60 percent of a replacement, replacement makes more sense.