What Keyless Go means
Keyless Go means "go without a key". You carry the key in your pocket or bag, and the car does everything it used to need the key in your hand for:
- You walk up to the car and take the handle. The doors unlock.
- You sit down, press the brake or clutch and the START button. The engine runs.
- When you get out, you touch the marked spot on the handle or the small button on it, and the car locks. Some cars also lock by themselves when you walk away.
Keyless-Go is the name Mercedes uses. Other brands call the same system something else.
The key still works as an ordinary remote: you lock and unlock the car with its buttons. There is usually a small metal key hidden inside it for the doors, in case the battery runs flat.
How the car recognises the key
The car has antennas that cover the area around the doors, the boot and the inside. When you take the handle, the car sends a weak signal through them. Some cars also send it on their own, at short intervals. The signal reaches only 1 to 2 metres from the car.
The key receives the signal and answers with a code that changes every time. When the answer is correct, the doors unlock.
To start, the car checks that the key is inside. If the key was left outside or a passenger who got out took it, the engine will not start. On many cars the dashboard then says the key is not in the car.
If the key stays in the car, some cars will not lock, so that you do not lock it inside.
Once the engine is running, it does not switch off if the key leaves the car, because switching off while driving would be dangerous. Some cars only beep or show a message.
Why a keyless car is a target for thieves
The car knows the key answered, but older systems do not measure how far away the key is. So thieves work in pairs: one gets as close as possible to your key, and the other stands by the car. Their devices relay the signal, so the car believes the key is next to it, unlocks and starts. More about keyless theft
In a test of about 700 keyless cars, the relay device opened more than 90% of them. Some newer cars resist it, because their key measures how far away it really is.
A running car does not switch off when the signal is lost, so the thief can drive it far away. This stops the thief:
An immobiliserThe engine will not start without your fob, which you carry separately from the key, even when a thief relays the key signal. More about the immobiliser- A key pouch that blocks the signalA key in the pouch does not answer the car, so the thief has nothing to relay. More about the key pouch
Keyless Go, keyless entry and keyless start: the difference
Not every car has the whole system. Some only open the doors without the key, and some only start the engine with a button.
| System | What it does |
|---|---|
| Keyless entry | The doors unlock when you take the handle, with the key in your pocket. |
| Keyless start | You start the engine with a button while the key is in the car. You open the doors with the button on the key. |
| Keyless Go | Both: doors and engine without taking the key out of your pocket. |
Check what your car has with the key in your pocket. If the locked car unlocks when you take the handle, it has keyless entry. If the engine starts with a button, without putting the key in the ignition, it has keyless start.
What your brand calls it
If one of these names is in your car's equipment, the car has keyless:
- Mercedes: Keyless-Go, and push-button starting only is Keyless Start
- Volkswagen: Keyless Access or KESSY
- Škoda: KESSY
- Audi: Advanced Key
- BMW: Comfort Access
- Hyundai: Smart Key
- Renault: a "hands-free" card instead of a key
Starting a car with a button
A car with keyless start is started with the START or START/STOP button:
- Keep the key in the car, in your pocket or bag.
- With an automatic gearbox, put the lever in P or N.
- Press the brake, and with a manual gearbox the clutch.
- Press the START button.
On some cars, pressing the button without the brake or clutch only switches on power, for example for the radio. The engine then does not start.
You switch the engine off when the car is standing still: lever in P, then press the same button.
While driving, one short press does not switch off the engine. In an emergency, switch the engine off by holding the button longer or with several quick presses. On some cars you hold the button for more than 2 seconds or press it 3 times within 3 seconds. Exactly how on your car is in the manual.
When the engine switches off while driving, the steering becomes heavy and the airbags do not work.
The START/STOP button and the start-stop system are not the same
The START/STOP button starts and stops the engine when you want. The start-stop system switches the engine off by itself when the car stands at traffic lights or in a jam, to use less fuel. With an automatic gearbox, the engine starts again by itself when you release the brake.
Can keyless be switched off
Whether keyless can be switched off depends on the car
- Mercedes: 2 quick presses of the lock button switch Keyless-Go off, and it comes back as soon as you press any button on the key.
- A key with a motion sensor: a key that stays still for 2 minutes no longer opens the car, and after 90 minutes it no longer starts it either. While you carry it, or right after you put it down, it still answers the car.
- Other cars: when keyless cannot be switched off, keep the key in a pouch. An immobiliser protects the engine even when a thief opens the car.
How it works on your car is in the manual.
Why keyless sometimes does not respond
- You pulled the handle too fastThe car did not have time to recognise the key. Take the handle, wait a moment, then pull it.
- The car has been parked for several daysSome cars then switch off the sensors in the handles to save the battery. The first pull on the handle wakes the car, and the second opens the door.
- A phone, headphones or another key are next to the keyDevices working on the same frequency disturb the signal. Keep the key away from them.
- The key works only when you are very closeThe key battery is getting weak. On some cars it lasts about a year.
The buttons on the key do not work eitherThe key battery is flat. The small metal key, hidden inside the key, opens the doors. The engine starts when you touch the START button with the key or put it on the spot marked for this in the car. Where that spot is on your car is in the manual. More about what to do when keyless does not work- The car battery is weakThe car then switches off secondary functions, so keyless may not open the doors even with a working key.
If the spare key with a new battery does not work either, the cause is in the car. Diagnostics show which part is not working. More about diagnostics
