A car key fob that has stopped working is usually a cheap fix, but it can also be the start of an expensive one if you choose the wrong route.
This guide explains why a key fob stops working, which fixes to try first, how to tell when it needs reprogramming and when to call an auto locksmith.
According to the RAC, a replacement fob battery costs £5 to £10, while a new fob can cost from £250 to well over £1,000.
Key Master is an auto locksmith Orpington drivers can call 24/7, and we cover Dartford and the rest of Kent and South East London too, so supplying and programming replacement fobs is part of what we do.
The short version is to check the simple causes first, and only pay for a new fob once they are ruled out.
Why Is My Car Key Fob Not Working?
The most common reason a car key fob stops working is a flat or weak battery. Other causes include a battery fitted incorrectly, damage or water exposure, a fob that has lost its programming and radio interference, according to the RAC.
• A weak battery. A fob can still start the car while remote locking and unlocking fail.
• A battery change gone wrong. The wrong battery, incorrect polarity or poor contact with the fob's terminals can all stop it working.
• Physical damage. A dropped fob or a cracked housing can break the circuit or the buttons. • Water damage. Moisture can damage the electronic components inside.
• Lost programming. A fob can fall out of sync with the car and need resynchronising or reprogramming. • Radio interference. This is mainly an issue for older fobs, and trying from a different position can help. Each cause has a different fix, so it is worth working through them in order.
How to Fix a Car Key Fob That Is Not Working
Start with the free checks, then replace the battery, then test and resynchronise the fob using your handbook. Most fob problems are solved at one of these steps, without paying anyone.
1. Move closer to the car, and try from a different position in case of radio interference. 2. Try your spare fob. If the spare works, the problem is with the first fob and not the car.
3. Check the battery number printed on the old battery, because fobs usually take a coin cell, but the size varies by vehicle.
4. Fit the new battery with the correct polarity, and make sure it sits firmly against the contacts. 5. Test the fob straight away, then check your vehicle handbook for resynchronisation steps if it still fails. 6. If it still does not work, stop and get it checked before you buy anything else.
The RAC notes that some vehicles need the key resynchronised after a battery change.
Why Is My Key Fob Not Working After Changing the Battery?
If a fob fails after a new battery, the cause is usually the wrong battery, incorrect polarity, poor contact with the terminals or a key that needs resynchronising. The RAC lists all four as common problems after a battery change.
• Check the number on the battery matches the old one exactly.
• Check the battery is the right way up.
• Check it sits firmly against the contacts, with no dirt or looseness.
• Check your handbook for a resynchronisation procedure.
If all four are fine and it still fails, the fob itself may be damaged or need professional reprogramming.
Signs Your Car Key Fob Needs Reprogramming
A key fob needs reprogramming when the car does not recognise it, even though the battery is good. Typical signs are that the doors will not lock or unlock, the fob works only intermittently, the car will not start or the security light blinks or stays lit.
The RAC says reprogramming typically takes between 30 minutes and an hour, depending on the make and model.
Some basic and older fobs can be reprogrammed at home by following the vehicle manual. For most modern cars, the RAC advises taking the key to a professional.
Reprogramming can fix software problems but not physical damage, which may need a replacement fob. The RAC's key programming guide explains the signs in more detail.
When Should You Call an Auto Locksmith About a Key Fob?
Call an auto locksmith if the fob still fails after a new battery and resynchronisation, if it is damaged or has been in water, if you need a spare or if you have lost it. A mobile locksmith can come to you, which matters if the car will not start.
• The fob still does not work after a correct battery change.
• The fob is cracked, worn or has been dropped in water.
• The car does not recognise the key and will not start.
• You have lost the fob or have only one working key.
• You want a spare programmed before the last one fails.
Key Master supplies and programs replacement and spare fobs where the vehicle and key system allow it, and we work at your home, workplace or roadside.
There is no callout fee, and you get a quote before work starts. Tell us the make, model and year, and we will confirm what is possible for your car.
Our spare and replacement car keys service covers fobs, remote keys and smart keys, and our emergency car key replacement service helps if you have no working key at all.
Auto Locksmith Orpington: Key Fob Help From Key Master
Key Master is a mobile auto locksmith Orpington drivers can call 24/7 for key fob problems, spare fobs and replacement keys. We come to your home, workplace or roadside, so a dead fob does not mean moving the car.
Searching for a car locksmith near me or a car locksmith Orpington? We cover both, and we travel across Kent and South East London.
If you need car key replacement near me, or car key replacement Dartford, give us the make, model and year and we will confirm what is possible.
Our average emergency response is under 30 minutes, although arrival depends on location and demand.
We cover Orpington, Dartford, Bexley, Sidcup, Gravesend, Bromley and more, and you can see all the areas we cover.
How Much Does It Cost to Fix or Replace a Key Fob?
A new battery usually costs £5 to £10, while a replacement fob costs far more. The RAC puts a new fob at from £250 to well over £1,000, including the fob and any related work, although the price depends heavily on your make and model.
Key Master does not publish fixed prices. Cost depends on the make, model, year, key type and programming needed, and we quote before work begins.
For a local benchmark, Checkatrade lists an average key fob in Orpington at about £160 and remote fob programming from £50 to £250.
These are general auto locksmith figures, not Key Master prices, so use them as a guide only. The RAC also says a locksmith is often more cost effective than going to a dealership.
Mistakes to Avoid When Your Key Fob Stops Working
Most of the money wasted on key fobs is spent before the simple causes have been ruled out. These are the mistakes worth avoiding.
• Buying a new fob before testing the battery and the spare.
• Fitting the wrong battery, or the right one the wrong way round.
• Ignoring the handbook, which may include resynchronisation steps.
• Continuing to use a damaged or water-damaged fob until it fails completely.
• Going straight to a dealer without asking a mobile locksmith for a quote.
• Waiting until the last working key fails before arranging a spare.
• Calling the first number you find without asking about callout fees and a quote.
Ruling out the simple causes first usually saves time and money.
If your keys are already inside the car, read what to do when your keys are locked in the car.
Call Key Master on 07713 582383 for key fob programming, a spare or car key replacement near you from your local auto locksmith in Orpington, Dartford and across Kent and South East London, or send a quote request if it is not urgent. You can also read our car key replacement guide or what to do if you have lost your car key.
