My Key Fob Stopped Working, Now What?

Fob Trouble

Take a breath, then start with the battery

When a fob goes quiet, the first suspect is almost always the small round battery inside it. These cells wear out gradually. You might notice that you have to stand closer to the car, press a button twice, or hear a delay before the doors respond. Then one day nothing happens at all. That slow fade is the classic story, and it is good news, because a battery is simple to change.

Look for a small slot or seam in the fob's case. Many open with a coin or a small flat tool, and some have a tiny screw. Inside, you'll see the cell with a number printed on it. Take it with you, or take a photo, and match it exactly. Pay attention to which side faces up before you remove the old one, since placing the new one backward will not work.

Be gentle with the plastic. Fob cases are meant to be opened, but they are not made for force. If it will not open easily, check the owner's manual or ask a technician, since pry marks on a case are permanent and a cracked case can let in moisture.

A small habit helps here: when you change a fob battery, do it somewhere calm, over a table, with a towel under your hands. The little springs and covers in some fobs travel a long way when dropped, and a lost button cover can be as annoying as a dead cell.

If the old battery looks swollen, leaking or discolored, wipe the contacts carefully and consider that moisture may have gotten in. A fob that has leaked is more likely to have lasting trouble, and a spare becomes more than a nicety.

Use the hidden key to get in

While you sort out the fob, you still need to get into the car. Most fobs hide a small mechanical key, usually released by a slider or a button on the side. The keyhole on the car may be under a cap on the driver's door handle, which you can often pop off carefully with the key blade itself. The manual shows exactly where.

Once the door is open, the alarm may sound because the car did not receive its usual signal. This is normal for some models. It may stop when you start the car or press the unlock button, or after a time. Keep calm, since it is a nuisance and not a sign of damage.

If you can't find the hidden key or the keyhole, don't pry at the door handle. A technician can show you where it is. Our page on locked out of your car explains how the visit goes when a fob failure leaves you outside.

Starting the car with a dead fob

Many push button cars have a backup way to start the engine when the fob battery is dead. Often there is a spot on the steering column, in the cup holder, on the console or near the start button where you can hold the fob to let the car read its chip at close range. The chip does not need a battery, which is why this works.

Hold the fob firmly against the marked spot, press the brake, and push the start button as usual. If your car has this feature, it should start. If you can't find the spot, the manual will show it, usually in a section about starting with a low fob battery.

If the car starts this way, you know the chip is fine and the remote buttons are the problem. That narrows the field a lot. Replace the battery, test the buttons, and you are likely done. If the car won't start even with the fob held to the spot, the chip, the antenna or the car's electronics are the more likely suspects. Our guide on what a transponder chip is explains why.

A few cars also let you unlock doors by pressing the physical start button or by using a door keypad if one is fitted. These details differ so much from car to car that the manual is the only reliable guide. Take ten minutes some weekend to read the page on fob failure, and mark it.

When a new battery does not fix it

Sometimes the new battery makes no difference. Check that the battery is fresh, seated flat, and facing the right direction. Check that the metal contacts inside the fob are clean and not bent. A bit of dirt or corrosion from a damp pocket can break the connection. Wipe gently with a dry cloth, not a liquid.

Some fobs lose their pairing when the battery is removed for too long, and some have a short re learn sequence in the manual. It may involve turning the ignition on and off in a pattern or pressing buttons in order. Follow the instructions exactly. If it works, you're done. If it does not, don't keep trying random sequences.

If the buttons do nothing and the car still starts with the fob held to the spot, the remote part of the fob may have failed or need pairing. That is a job for programming equipment, and our key programming and fobs page explains what is involved.

Signs of physical damage

Fobs live hard lives. They get dropped, sat on, sent through the wash, left in hot cars and chewed by dogs. Look at yours. Is the case cracked? Are the button covers worn through? Is there moisture or green corrosion inside? Is the circuit board visibly bent or the battery holder loose?

Water is a frequent cause. A fob that went through the wash may work again after drying completely, but it can fail days later as corrosion develops. If yours was soaked, open it, let it dry in a warm, dry spot away from direct heat, and test it. If it revives, have a spare made soon.

A cracked case sometimes can be moved to a new shell, which restores the look and the feel. A cracked board is another matter. The technician can tell you whether repair or replacement is wiser, and you can read more in our guide to when to repair or replace for a similar way of thinking.

If you are not sure how long the fob has been getting weaker, think back over the past few weeks. Did the range shrink gradually? Did it only fail after a specific event? A gradual fade points to the battery, while a sudden stop points to damage or pairing. Telling that story clearly is the most useful thing you can do.

Interference and odd environments

Sometimes the fob is fine and the surroundings are the problem. Strong radio signals, large metal structures, and busy parking areas can interfere with the short range link between fob and car. If the fob works at home and fails in one particular parking lot, the lot is the likely culprit.

Try moving a few steps, standing closer to the car, or holding the fob near your body or head, as the human body can sometimes help the signal. Remove other fobs, large metal tags or magnets from the key ring, which can crowd the signal. These tests cost nothing and take seconds.

If the problem follows you everywhere, return to the battery and the pairing. The pattern of when it fails is itself information, and a technician will appreciate hearing it.

If the fob works only in some places, make a note of them. A pattern, such as failing near a particular building but working fine elsewhere, is a strong clue that the surroundings are to blame and the fob is healthy. Share that note with anyone who helps.

The car side of the story

A fob problem is not always a fob problem. A weak car battery can make the doors behave oddly, and the car may ignore a perfectly good fob. A blown fuse, a faulty door module, or a damaged antenna can cause similar symptoms. Test your spare fob if you have one. If the spare works, the first fob is at fault. If neither works, look to the car.

If the car's own battery is weak, you may notice dim lights, slow cranking, or other warning signs. Charging or replacing the battery could resolve things. Beyond that, a technician with diagnostic equipment can read the car's modules and find the cause.

This is why the spare matters so much. It turns a vague mystery into a clear test, and the answer tells you where to spend your effort. If you don't have a spare, now is a good time to arrange one.

Cold, heat and the local climate

Weather affects fobs more than people expect. Cold weakens batteries, so a fob that worked in autumn may falter on a freezing morning in Dunsmuir or Weed. Warming the fob in your hand or pocket for a moment can bring it back temporarily, and it is a hint that the battery is nearing the end.

Heat is hard on electronics. A fob left on a sunlit dashboard in a Redding summer can overheat, warp its case or damage its board. Try to keep fobs out of direct sun, and don't store them in a hot glove box.

Moisture is common in the wetter months and in the mountains. A damp pocket, a snowy trail, a mud puddle or a wet jacket all invite trouble. Our pages on Dunsmuir and Weed describe some of what mountain conditions do to locks and keys.

Do not forget the less obvious car side culprits, such as a key shaped warning on the dashboard, a door that reports itself open when it is closed, or a trunk latch that is not fully engaged. A car that believes a door is open may refuse to lock, and that can look exactly like a fob failure. Check that every door, the hood and the trunk are closed properly before blaming the fob.

When it is time to ask a locksmith

If you have changed the battery, tried the hidden key and the starting spot, checked for damage and interference, and the fob still will not work, it is time for help. A technician can test the fob, read the car, and tell you whether to repair, re pair or replace. The service van carries key cutting and programming equipment, so many fob jobs can be handled at the car.

Gather the car's make, model and year, the fob or key you have, and any spares. Note what you have tried and what the car does. Our guide on what to have ready lists more helpful details.

A phone line for Redding Mobile Locksmith is coming soon, so for now the request form is the way to ask. Our page on replacement car keys describes what a new key involves.

Preventing the next failure

A few habits go a long way. Replace the fob battery on a schedule you set for yourself, say once a year at a date you will remember, rather than waiting for it to fail. Keep a spare key somewhere safe and test it now and then. Don't hang a heavy bundle of keys from a fob, since the weight wears the ignition and the fob's case.

Protect the fob from water, heat and drops. A simple silicone cover can soften knocks. Keep it away from strong magnets and out of the pocket you use for a wet phone. And learn where the hidden key and the backup start spot are before you need them.

None of this is fussy. It is the same sort of simple care you give to a flashlight or a smoke alarm, and it keeps small things from becoming big ones. If you want more on how keys and cars work together, read whether all car keys need programming.

Lastly, think about the lanyard or key ring. A fob that swings freely against other metal keys all day takes small knocks that add up over the seasons. Giving it its own loop, or keeping it in a pocket apart from loose change and tools, is an easy way to give it a longer life.

A scenario to picture

Imagine a driver who finishes a long shift, walks to the car on a frosty evening, presses the unlock button and gets nothing. They press again, hold the fob up in the air, even press it against their chin, a trick many people swear by. Still nothing. They pull out the hidden key, open the driver's door, and the alarm complains for a minute.

Calmly, they hold the fob against the start spot, press the brake and the start button, and the engine catches. The next day they change the battery with a coin and a ten minute search for the right size, and the buttons wake up. Cost and drama are both small, because they took the steps in a sensible order.

Now imagine the same driver skipping the battery, believing the fob is ruined, and ordering a replacement. A few days and a fair bit of money later, the new fob arrives and needs programming, and the old one would have worked with a fresh cell. Most fob troubles are the first story. A few are the second, and a few are something else entirely. The order of checks above is how you tell which you have.

If your own checks lead to a real failure, you are not alone, and it is a routine job. Our page on cars and trucks shows the range of vehicle work the team handles, and the guide on how a car is opened without the key explains the other side of a bad day.

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Common questions