Why keyless does not work: sign and cause
Keyless is a system that unlocks the car and starts the engine while the key is in your pocket.
Neither the handle nor the button on the key worksMost often the battery in the key is flat. The same goes when the car only sees the key once you are right next to the door.
Nothing works: not the handle, the central locking or the lights in the carThe car battery is flat. Keyless then does not work even with a working key. More about car battery replacement- It works in one place but not in anotherA strong signal nearby interferes: a radio transmitter, an airport, a phone or another key next to yours.
Only one door does not openThe other doors see the key, so the key works. The fault is in that door handle or in the cables to it.
The key was dropped or got wetWater and a fall can damage the key inside. The key then does not work even with a new battery.- The spare key does not work eitherWhen the spare key also has a new battery, the cause is in the car. Diagnostics shows us which part is not working. More about diagnostics
Dashboard messages when the car does not see the key
The wording depends on the make of car.
- “Key Battery Low” or “Low key battery”The battery in the key is running out. Change it before the car stops seeing the key.
- “Key not detected”The car does not see the key when you press START. Start it by pressing the START button with the key itself.
- “Press START button with key”The car wants you to press the START button with the key itself. The immobiliser light also flashes.
- “Key not in vehicle”The car thinks the key is not inside. The car does not always see a key that is in the glovebox, a door pocket, on the floor or on the dashboard.
- “Press START button whilst turning wheel”The steering wheel did not unlock. Press START while moving the wheel left and right.
- “Press brake pedal” or “Press clutch pedal”The engine does not start until the brake, and the clutch on a manual, is pressed all the way down.
- “Smart Key System malfunction”The system has reported a fault. With diagnostics we read the error it has stored.
How to open the car when keyless does not work
A mechanical key is hidden in the key. It slides out when you press a small button or move a catch on the key.
Where the lock is and what opens depends on the car
- The lock is on the driver's door, often under a plastic cap at the end of the handle that you remove with the mechanical key.
- On some cars you press a button under the handle with the key and pull the cap towards you.
- If the car has not been used for 14 days or more, some cars open only the driver's door with keyless.
The mechanical key has grooves on one side only. If it won't go into the lock, turn it over.
How to start the car with a flat key
- Press the brake pedal all the way down, and the clutch too on a manual. Hold them until the engine starts.
- Touch the START button with the key. On some cars the side with the maker's badge faces the button.
- When the car recognises the key, on some cars a short beep sounds or a green light comes on in the button.
- While the key touches the button, press START. If the engine does not start, begin again from the first step.
This works because the chip in the key needs no battery when the key is very close. While starting this way, no other key, metal or card may touch the key, because then the car does not receive the signal.
This gets you through the day. The battery needs changing straight after.
If the engine does not start this way either, try the spare key. If it does not start with that one, the car does not recognise the keys and we check the immobiliser. More about when the car won't start because of the immobiliser
Changing the car key battery
The battery in a keyless key runs down even when you do not use the key, because the key keeps receiving the car signal. It lasts about 1 to 2 years.
Signs that the battery is getting weak:
- The dashboard says the key battery is low.
- The car only sees the key when you are very close.
- The button on the key works only sometimes.
- The light on the key does not come on when you press a button.
The dashboard message may not appear in time. That is why it is good to change the battery once a year.
The key can be damaged while the casing is opened, and a new keyless key has to be made and programmed to the car. That is why some car makers advise against changing the battery yourself. We change the battery in the key, and the casing when it is broken. More about the car locksmith
If the key does not work even with a new battery but the spare does, the fault is in the first key: it is damaged or needs to be programmed into the car again. More about key programming
What else interferes with the key
The key and the car talk over a weak radio signal. Anything that covers or overpowers it interferes with keyless.
- A phone next to the keyIt interferes most while you are on a call or sending messages. Carry them in different pockets.
- A device or charger switched on within 10 cmThis includes a device plugged into the car's power outlet. Move the key away from it.
- Metal next to the keyCoins, a metal wallet or a card with foil. Take the key out and try again.
- Another keyless key next to yoursThe car then unlocks more slowly or not at all. Keep the keys apart.
- The key has not moved for a long timeOn some cars a key that does not move stops responding. Pick it up and try again.
- Gloves, ice, snow or mud on the handleThe handle then does not sense the touch. Clean it and touch it with a bare hand.
- Window tint film with metal in itThe key only works closer to the car.
- A key pouchWhile the key is inside, the car does not see it. That means the pouch works. More about the key pouch
A thief can use a device to block the key signal while you lock, so the car stays unlocked. So pull the handle after locking.
Do not leave the key near the car: while it is in range, anyone can open the doors, and the car battery can go flat. More about theft protection
When the fault is in the car
When both keys have new batteries and keyless still does not work, the fault is in the car. Keyless in the car has antennas in the door handles and in the cabin, and its own control unit, which stores errors, and the fault is in one of these parts.
- Antenna in the door handleOnly that door won't open, the others work.
- Touch sensor in the door handleWhen moisture gets into the handle, the car does not lock on touch, and it works again once the handle dries.
- Antenna amplifierThe car only sees the key when you hold it against the driver's door.
