A car comes out of anti theft mode with the key after 10 to 15 minutes at ignition on, or 20 to 30 seconds held in the driver door lock.
Three checks come first, the spare key, the key fob battery and the car battery. The ignition reset and the door lock method take four steps each. Push button start cars reset with the fob against the start button. Each dashboard warning points to one fault. Anti theft mode stays on where the immobiliser receives no correct code. A key that fails every reset requires recoding, and ADC Locksmith Liverpool provides car key programming in Liverpool at the car.
A battery disconnect, a new car battery, a dead fob battery, key replacement and an auto locksmith raise the further questions about anti theft mode.
The list below gives four key takeaways on a car stuck in anti theft mode.
- The spare key, the fob battery and the car battery come before any reset.
- The ignition reset takes 10 to 15 minutes at the on position.
- The door lock method takes 20 to 30 seconds at unlock.
- A reset clears a temporary lockout and does not repair a failed chip.
Which checks come before a reset?
Three checks come before a reset, the spare key, the key fob battery and the car battery. The list below gives the three checks in order.
- The spare key starts the car where the chip in the main key has failed.
- A new coin cell in the key fob restores a weak signal.
- A car battery under 12 volts corrupts the key check, and a charge or a jump start clears the fault.
How do you reset anti theft mode?
To reset anti theft mode, turn the key to the on position and wait 10 to 15 minutes. The list below gives the four steps.
- Insert the key and turn the ignition to the on position without cranking the engine.
- Leave the key at on for 10 to 15 minutes and watch the security light.
- Turn the key off for 5 seconds once the security light stops flashing.
- Start the engine, and repeat the cycle up to three times where the light keeps flashing.
The cycle clears a temporary lockout. A failed chip or an uncoded key stays locked out after every cycle.
How do you use the door lock method?
To use the door lock method, hold the key in the driver door lock at unlock for 20 to 30 seconds. The list below gives the four steps.
- Insert the key blade in the driver door lock from outside the car.
- Turn the key to unlock and hold for 20 to 30 seconds.
- Turn the key to lock and hold for 20 to 30 seconds.
- Remove the key, sit in the car and start the engine.
The door lock tells the car that the correct key holder is present, which silences an alarm that the remote failed to disarm.
How do you reset push button cars?
To reset push button cars, hold the key fob against the start button and press the button with the brake down. The list below gives the three steps.
- Press the brake pedal, or the clutch on a manual car.
- Hold the key fob flat against the start button or in the backup slot.
- Press the start button with the fob in place.
The backup reader powers the chip in the fob without the fob battery. The handbook shows the backup position for each model.
Which warning means which fault?
Each warning points to one part of the system, the key, the car battery or the immobiliser. The table below gives five warnings with the usual cause and the first step.
| Warning | Usual cause | First step |
|---|---|---|
| Key or padlock light flashing fast | Chip in the key not read | Spare key |
| Service theft deterrent system message | Low car battery or key not recognised | Charge the car battery |
| Immobiliser active message | Key not coded to the car | Spare key, then recoding |
| Key not detected message | Flat key fob battery | Fob against the start button |
| Alarm sounding and engine dead | Alarm not disarmed by the remote | Key in the driver door lock |
A warning that returns after every reset points to a fault in the key chip, the reader ring or the immobiliser.
Why does anti theft mode stay on?
Anti theft mode stays on because the immobiliser does not receive the correct code from the key. The list below gives the five causes in order of frequency.
- A flat key fob battery sends a weak signal or none.
- A worn or damaged key carries a chip that the reader no longer reads.
- Low car battery voltage breaks the exchange between the key and the immobiliser.
- A forced door or a wrong unlock sequence trips the alarm.
- A faulty reader ring, wiring or immobiliser module blocks every key.
When does the key need recoding?
The key needs recoding when the spare key starts the car and the main key does not, or when no reset holds.
Recoding matches the chip in the key to the immobiliser through the diagnostic port. ADC Locksmith Liverpool carries out car key programming in Liverpool at the car, and a recoded key ends the lockout for good.
What else affects anti theft mode?
The car battery, the fob battery, a damaged chip and the spare key raise further questions about anti theft mode. The eight questions below answer each case.
Frequently asked questions
How long does an anti theft reset take?
An anti theft reset takes 10 to 15 minutes for one ignition cycle and up to 45 minutes for three cycles.
Does a battery disconnect reset anti theft mode?
Yes, a battery disconnect of 15 minutes clears a temporary anti theft lockout on some cars.
The disconnect also clears the clock and the radio presets.
Does anti theft mode switch off permanently?
No, anti theft mode does not switch off permanently, because the immobiliser sits inside the engine control unit.
Removal of the immobiliser also affects the car insurance.
Does a new car battery trigger theft mode?
Yes, a new car battery triggers anti theft mode on some cars, because the power loss resets the security module.
The key in the driver door lock or one ignition cycle clears the lockout.
Does a damaged chip need key replacement?
Yes, a damaged chip requires key replacement, because no reset repairs a transponder chip.
ADC Locksmith Liverpool cuts and codes a key replacement at the car.
Does a dead fob battery trigger theft mode?
Yes, a dead fob battery triggers anti theft mode on keyless cars, because the car receives no code.
A dead fob battery still starts most cars from the backup position.
Does a spare key clear anti theft mode?
Yes, a spare key clears anti theft mode where the fault sits in the main key.
A spare key that also fails points to the car.
Who fixes anti theft mode at the car?
An auto locksmith fixes anti theft mode at the car.
The auto locksmith reads the fault, tests the spare key and codes a working key, and anti theft mode ends.
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