Why Won't My Key Fob Work?

What a Key Fob Does

A key fob is a small radio remote that speaks to your car. When a button is pressed, the fob sends a coded signal, and the car checks that signal before it opens the doors or lets the engine start. A smart key works in a like way, except the car senses the key while it stays in a pocket, and the engine starts at the touch of a button. The fob also holds a chip that the immobiliser checks, so the fob is both a remote control and a key in a single case.

Because the fob carries out two jobs at once, a fault can show itself in two ways. The buttons may fall silent while the key blade still turns in the lock, or the car may refuse to start even though the doors open. Noting just what works and what fails is the most useful thing you can do before you ring, because it points to the cause. A fob that does nothing at all points to the cell, while a fob that opens the doors yet will not start the car points to the chip or the link between fob and car.

The fob needs power to send its signal, and that power comes from a small coin cell inside the case. The cell lasts a long time, and it fades bit by bit rather than failing in one moment. The opening sign is often a shorter range: you have to stand nearer the car than before. The next sign is a button that needs two presses in place of one. When the range shortens or the buttons feel slow, the cell is the opening thing to check.

Step One: The Battery

Begin with the cell, because it lies behind the largest share of fob faults and it is the one fix you can carry out yourself. Look in your handbook for the cell type your fob needs, then open the fob case as the handbook shows and fit the new cell the same way round as the old one. Shut the case and test the fob by locking and unlocking the car. When the fob works again, the job is finished.

Buy the right cell type, not merely a cell that looks the same size. The handbook names the type, and the old cell carries the same marking on its face. A cell that has sat nearly flat in a drawer will not mend the fault, so use a fresh one. When the fob works with the new cell for a day and then falls silent again, the fob itself may be draining power badly, and that is a fault for a locksmith to look at rather than a second cell.

When a new cell changes nothing, stop buying cells. The cause lies further down the ladder, and the next stages are to check the range, look for harm, and then ring for help. A fob that stays dead after a fresh cell holds a fault that a cell cannot mend.

Step Two: Range and Signal

A fob that answers only when you stand close to the car may hold a weak cell, or something may be blocking the signal between fob and car. Try the fob away from other electronics, and try it from different sides of the car. A phone, a tablet, or a metal case carried beside the fob can block the signal, and so can a second fob pressed against it in the same pocket.

Strong radio signals close by can also drown out the fob. A car park full of cars, a building with heavy electrical kit, or a street with strong transmitters can all cut the range short for a while. When the fob works as normal once you shift to a different place, the fault lay in the setting, not the fob. When the range stays short everywhere you try it, the fob or the receiver in the car needs a closer look, and that is the moment to ring 07367 634032.

Step Three: Damage to the Fob

A fob rides in a pocket each day, so it meets knocks, drops and water that a plain key blade never faces. A fall onto hard ground can split the case or shake a part loose inside, while a fob that has been through the wash can give up days later, once water has reached the electronics. Look over the case for splits, check that each button presses cleanly, and listen for a rattle when you shake the fob gently.

Harm from water is the hardest fault to spot from outside, because the case can look sound while the parts inside are wet. When the fob has been through the wash or fallen into water, stop pressing the buttons, because that can drive water further into the case. Dry the outside, take the cell out when you can, and ring for advice. A fob that has been harmed may need a key fob replacement in Rednal, Birmingham, and the new fob will have to be coded to the car before it works.

• Split case or loose buttons after a fall onto hard ground
• Damp inside the case after rain, a spill, or a trip through the wash
• A rattle when shaken, which can mean a part has come loose inside
• Buttons that stick, feel soft, or ask for a hard press

Step Four: When to Call a Locksmith

Ring a locksmith once the cell, the range, and the harm checks have all been tried and the fob still stays silent. Describe what the fob does and what it fails to do, whether the key blade still turns in the lock, and whether you hold a spare key that works. Those three facts point to the cause sooner than any other detail, and they help us settle what the visit needs.

A locksmith can test the fob, check whether the chip still speaks to the car, and code a new fob where the vehicle allows it. When the fob cannot be saved, a replacement can be supplied, cut, and coded in one visit, and tested before we leave. Tell us the make and model when you ring and we will give an honest answer about whether we can help with your car. When you need a spare made while the fob is being looked at, read the spare car key page for Rednal, Birmingham first, because a working spare changes the whole job.

What Not to Do

Never prise the fob open with force, because the case clips snap easily and a broken case lets in water and dirt. Never fit a cell the wrong way round, because the fob will stay silent and the cell can be harmed. Never buy a cheap coding device online and try to pair the fob yourself, because a single slip while pairing the fob can leave the car refusing every key, even a sound one.

Never brush aside a fob that works only some of the time. A fault that comes and goes is still a fault, and it tends to fail outright at the worst moment, such as late at night or far from home. When the fob is unreliable, get it looked at while you still hold a working spare. You can also read the car key programming page to see how a fob is paired to a car, and why that stage calls for the right kit.

• Action Fraud: report key and vehicle crime
• Citizens Advice: consumer guidance

What This Means in Rednal, Birmingham

A dead fob in Rednal, Birmingham B45 is seldom a reason to tow the car anywhere. The car stands at home, at work, or in a local car park, and a mobile locksmith travels to the car to test the fob and code a replacement beside it. Keep the handbook details and the spare key in mind when you ring, because they shape the visit.

When your fob has fallen silent and the checks above have not mended it, ring 07367 634032. Say where the car stands, what the fob does, and the make and model. When the trouble turns out to be the charge for a new fob rather than the fault itself, the car key replacement cost guide sets out the influences that shape the charge. For a pressing lockout rather than a fob fault, the emergency auto locksmith page for Rednal, Birmingham is the right place to start.