Why Is My Key Fob Not Working?
A key fob that suddenly stops working is frustrating — especially if it happens in a parking lot or away from home. Before calling a locksmith, there are a few quick checks that can save you time and money. Here are the most common causes and how to address each one.
1. Dead Battery (Most Common)
A dead or weak battery is the cause of the vast majority of key fob failures. Most fobs use a CR2032 lithium coin cell battery that lasts 1–3 years. Signs of a dying battery include reduced range (the fob only works when very close to the car) before it stops entirely.
Fix: Replace the battery yourself. A CR2032 costs at any pharmacy, grocery store, or hardware store. Open the fob along the seam with a small flathead screwdriver or coin, swap the battery (match the + side orientation), and test. Takes about 2 minutes.
If the new battery fixes it, you're done. If not, keep reading.
2. Fob Lost Its Programming
Key fobs can lose their programming if the car battery completely died and was disconnected, if the vehicle's BCM (Body Control Module) was reset, or occasionally after certain electrical events. The fob itself is physically fine — it just needs to be re-synced to the car.
Fix: Some vehicles allow you to re-sync the fob yourself via a key sequence (check your owner's manual for a "fob programming" procedure). If your vehicle doesn't have a DIY programming mode — common on newer cars — a locksmith can reprogram it at your location using an OBD diagnostic tool. Typical cost: .
3. Damaged Internal Circuit
If the fob was dropped on a hard surface, got wet, or has visible cracks, the internal circuit board may be damaged. A new battery won't help if the circuit is broken. In this case, you need a replacement fob cut and programmed.
Fix: A locksmith can supply an OEM-equivalent replacement fob and program it at your location. Cost: depending on your vehicle make
4. Signal Interference
In rare cases, strong RF interference from nearby electronics, power lines, or other sources can temporarily block the fob signal. This is almost always a location-specific issue — if the fob works in some places but not others, interference may be the cause.
Fix: Move the vehicle or try using the fob from a different location. This issue resolves itself and doesn't require a locksmith.
5. Vehicle Receiver Issue
If you've already tried a new battery, re-programming, and tested a second fob that also doesn't work — the car's key fob receiver module may be faulty. This is relatively rare but does happen on older vehicles.
Fix: This requires a diagnostic visit. Call us and we can do a basic fob signal test at your location to determine whether the issue is the fob or the receiver.
Key Fob for Push-to-Start Vehicles: Hidden Backup Key
If you have a push-to-start vehicle and the fob dies completely, you can still start your car. Most push-to-start vehicles have a hidden backup:
- A physical key blade hidden inside the fob (press the release button to extract it) — use to unlock the door manually
- A key card slot or NFC zone on the start button or console — hold the dead fob directly against it to start the car
Check your owner's manual for the exact procedure for your vehicle.