Smart or proximity key not detected

If your car cannot detect the smart key and push button start will not respond, the usual culprits are a weak key battery, a damaged fob, a flat vehicle battery, or interference. Many cars also have an emergency start method in the owner’s manual. Here is what is safe to check and when a mobile locksmith in Brisbane can help.

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Reviewed by the LockOps automotive locksmith team · Published August 2026 · Last reviewed August 2026. General guidance only. The cause cannot be confirmed without inspecting the vehicle.

Does this sound like your problem?

Push button start does nothing, or shows a key not detected message.
The car finds the key sometimes and not others.
The key was dropped, got wet, or is cracked.
The doors will not unlock as you walk up to the car.
The car has been sitting a while and the battery may be low.

Possible causes

These are the usual categories, not a diagnosis. Which one it is can only be confirmed by checking the car and the key.

Weak key battery

The most common cause. A tired fob battery makes the signal too weak to detect.

Damaged or wet key

A knock or moisture inside the fob can stop it transmitting properly.

Wrong or unprogrammed key

A key that is not paired to this vehicle will not be detected.

Vehicle battery condition

A flat or weak car battery can stop the car detecting the key at all.

Interference

Other fobs, phones or wireless chargers nearby can interfere with detection.

Many push button cars have an emergency start method for a flat fob battery, usually holding the key against a marked spot or the start button. It is set out in the owner’s manual for your model. It is worth checking, and it is a normal manufacturer feature, not a security workaround.

Safe checks you can do

Fit a fresh key battery of the correct type.
Move other fobs, phones and wireless chargers away from the key.
Check the owner’s manual for the emergency start method.
Hold the key where the manual says as you press start.
Try a spare smart key if you have one.

What to avoid

Do not follow any online immobiliser or security bypass method.
Do not press start over and over hoping it catches.
Do not prise the fob open roughly and damage the board.
Do not ignore a flat or weak vehicle battery.
Do not assume the key needs replacing before the battery is checked.

What an automotive locksmith can check

Whether the fob is faulty and needs replacing.
Whether it needs reprogramming to the car.
Whether a spare or a new smart key is the right fix.

When another trade may fit: a flat vehicle battery is a roadside job, and a deeper detection or electrical fault may need an auto electrician or dealer. We will tell you if that is where it points.

To quote this accurately we need the make, model and year, that it is push button start, how many smart keys you have and whether any work, exactly what happens, and where the car is.

Get it sorted

Smart and proximity keys →Fob supplied, coded or replaced for push button cars.

Key programming →Recode the smart key so the car detects it.

Key replacement →A new smart key if the fob has failed.

Remote key fobs →Fob battery, buttons and case sorted.

Questions

Why will my car not detect the smart key?

Most often a weak fob battery, and after that a damaged fob, a flat vehicle battery, or interference from other devices. These are categories rather than a diagnosis, confirmed by checking the car and key.

Can I start the car with a dead fob battery?

Many push button cars have an emergency start method in the owner’s manual, usually holding the fob against a marked spot or the start button. Check your manual for your model. If there is none, or it does not work, give us a call.

Do I need a new smart key?

Not always. It is often a battery or a reprogram. Sometimes the fob has failed and needs replacing. We test it on site and tell you which.

Car not finding your smart key?

Tell us your make, model and year. We will tell you what is likely and what your car needs.