A car does not unlock with the remote or the key because of a flat fob battery, a flat car battery or a seized door lock. The emergency blade inside the key fob opens most cars by hand.
A flat coin cell, worn buttons and a lost pairing stop the remote. A seized barrel and a worn blade stop the key. The symptom shows the side at fault, the key fob, the central locking or the lock. The emergency blade opens the driver door. A resync or fob repairs restore the remote. An auto locksmith opens the car, and a garage repairs the wiring.
A car with a dead battery, cold weather, the immobiliser and a flat key fob battery raise the further questions about a car not unlocking.
The list below gives four key takeaways on a car not unlocking with the remote or the key.
- A flat coin cell in the key fob is the most common cause of a dead remote.
- A flat car battery stops the central locking, and the mechanical door lock still works.
- The emergency blade in the fob opens the hidden keyhole under the driver handle cap.
- A second fob separates a fob fault from a fault in the car.
Why does the remote stop unlocking the car?
The remote stops unlocking the car because the fob has no power, no signal or no pairing. The list below gives the five causes in order of frequency.
- A flat coin cell in the key fob weakens the signal before the remote fails.
- Worn buttons or a cracked circuit board stop the fob sending a signal.
- A lost pairing leaves the fob sending a code the car no longer accepts.
- A flat car battery leaves the central locking without the 12 volts the lock motors require.
- Radio interference near masts blocks the signal for a moment.
A second fob that works points to the first fob, and two dead fobs point to the car.
Why does the key not turn the lock?
The key does not turn the lock because the barrel has seized, the blade has worn or ice has frozen the mechanism.
A seized barrel follows years without use, and a worn blade no longer lifts the pins. A key that turns freely points to a rod that has come off the latch.
Which fault matches which symptom?
Each symptom points to one side of the system, the key fob, the car or the door lock. The table below gives six symptoms with the likely cause and the fix.
| Symptom | Likely cause | Fix |
|---|---|---|
| Remote dead, key opens the door | Flat fob battery | New coin cell |
| Remote works only beside the car | Weak fob battery | New coin cell |
| Both fobs dead, dashboard dark | Flat car battery | Blade in the door, then a jump start |
| Fob starts the car, doors stay locked | Worn unlock button or failed door actuator | Fob repair or actuator |
| One door stays locked | Failed door actuator in that door | New actuator at a garage |
| Key turns, door stays shut | Seized barrel or loose rod | Lock repair by an auto locksmith |
Central locking that clicks without moving the locks points to a door actuator, and silence points to a fuse or the wiring.
How do you open the car by hand?
To open the car by hand, slide the emergency blade out of the fob and turn the lock under the driver handle cap. The list below gives the four steps.
- Press the release catch on the fob and slide out the emergency blade.
- Find the slot under the cap on the driver door handle.
- Prise the cap off from the slot with the tip of the blade.
- Turn the blade in the lock and pull the handle.
How do you resync a key fob?
To resync a key fob, fit a new coin cell, stand beside the car and press the unlock button several times. The list below gives the three steps.
- Fit a new coin cell of the type printed on the old cell.
- Stand beside the driver door and press the unlock button four times.
- Turn the ignition on and press the lock button, on models with a keyed ignition.
A fob that stays dead after the sequence requires diagnostic equipment, and ADC Locksmith Liverpool carries out fob repairs and pairing at the car.
Who repairs a car that stays locked?
An auto locksmith and a garage repair different halves of a car that stays locked. The list below gives the three jobs and the trade for each.
- An auto locksmith opens the locked car and repairs the fob, the key and the door barrel.
- A garage or an auto electrician replaces a door actuator, a fuse or broken wiring.
- A garage tests and replaces the car battery.
What else stops a car unlocking?
A dead car battery, cold weather, the immobiliser and a flat fob at the start button raise further questions about a car not unlocking. The nine questions below answer each case.
Frequently asked questions
Why does a new battery not help?
The remote fails with a new battery because the fob has lost the pairing or the fault sits in the car.
What opens a car with a dead battery?
The emergency blade in the driver door opens a car with a dead battery, because the mechanical lock works without power.
A car with a dead battery and no blade in the fob requires entry by an auto locksmith before the jump start.
Why does the key fail in the lock?
The key fails in the door lock because of a seized barrel, a worn blade or a frozen lock.
Can cold weather stop a car unlocking?
Yes, cold weather stops a car unlocking when ice forms inside the lock or on the door seal.
A lock de-icer frees the barrel, and steady pressure on the door breaks the ice on the seal.
Why does the spare fob fail as well?
The spare fob fails as well because the fault sits in the car, in the receiver, the central locking or the car battery.
What opens the car when both fail?
An auto locksmith opens the car when the remote and the key both fail, through entry that leaves the door, the glass and the lock undamaged.
Does the immobiliser stop the doors unlocking?
No, the immobiliser does not lock the doors, because the immobiliser controls the engine start and the central locking controls the doors.
An alarm fault keeps some cars locked until the blade disarms the system.
Which test separates fob and car faults?
A second fob separates a fob fault from a car fault.
One dead fob points to that fob, and two dead fobs point to the car.
Does a flat key fob battery stop starting?
No, a flat key fob battery does not stop most cars starting, because the chip inside the fob works without the battery.
A flat key fob battery leaves the central locking silent and the start working on most cars. An auto locksmith tests the key fob at the car when both functions fail.
Based in Liverpool and still stuck?
ADC Locksmith Liverpool repairs, programs and replaces car keys at the roadside across Liverpool and Merseyside, usually on the same day. Craig Evans holds SERMI approval and a 5.0 rating from over 300 Google reviews. A call to 07731 544220 brings a fixed price before Craig travels.
Call 07731 544220