G28CarKeys should be left to auto locksmiths with experience who have the appropriate equipment and know-how. They will be able to create and program new keys faster than a dealership would and at a cheaper cost.
A dead battery for your coin is the most likely cause when your key fob stops locking or unlocking the doors. There are many other reasons that the key could be malfunctioning.
Dead Coin Battery
A dead battery in the coin compartment will prevent your Peugeot 208 from locking or unlocking and will not allow you to start the engine. If this is the case, you'll need to make use of the backup starting procedure that is detailed in the owner's manual of your vehicle.
Another reason your 208 might not be starting is because the spark plugs are been worn down. The spark plugs are responsible for sparking the fuel which starts the engine. However they are limited in their lifespan. They will eventually break down if they aren't used frequently enough.
There is a simple solution for this problem. Examine the voltage of your battery with a multimeter. If it's below 11.5 volts then you must replace it. It is also essential to clean the contacts of the battery in case it is corroded. This can be done by lifting the rubber covers covering the two terminals of the battery and using a wire brush to remove any corroded parts of the battery. Then, you must reconnect the positive pole cables to the negative.
Water Damage
If your 208 won't turn on and the battery is not flat, then you need to make sure whether the spark plugs work. You may find that they're filthy and don't spark. This can be fixed easily by cleaning the spark plugs in an workshop.
Peugeot automobiles use a key with a transponder compatible with the immobiliser. This ensures that only the right key is able to turn the engine. If the chip inside the Peugeot key is damaged, it will not transmit the correct signal to the vehicle.
Water damage is a typical reason for this issue. This is a frequent issue in areas with colder temperatures where the vehicle is exposed to snow or rain. If this is the case, you should seek out a reputable auto locksmith who has all of the tools and equipment needed to reprogram the new key. They will also have the latest technological know-how and the equipment required to create a Peugeot 208 smart key. The process shouldn't be more than 15 minutes.
Contacts with the battery may be damaged.
Peugeot replaced the transponder chips by introducing a new model that utilizes electronic components that are mounted on a circuit board. This new system works well when it's brand new, but over time the circuit boards begin to wear out and stop functioning correctly.
This can stop the immobiliser from triggering so that the vehicle won't start. Contact a Peugeot specialist or a locksmith if this is the situation.

A common issue occurs when the battery inside the key fob starts to fail. This causes the blade of the key to stop feeding into the lock. A car locksmith can replace the battery and cut a new blade for you, this is normally a quick fix.
Faulty Receiver Module
It could be that the receiver module is defective If your Peugeot key fob stops working after being dropped on the floor, or exposed to a sudden downpour or accidentally washed. The receiver is responsible for transmitting radio frequency signals to the onboard computer that controls the central locking system within your Peugeot vehicle.
Rubber seals on the key fob prevent water from reaching the electronic chip. However prolonged exposure to water can be able to penetrate these seals and cause damage to the chip. Submerging the key fob into ocean water at the beach or throwing it into the pool could be particularly damaging due to the high salt content.
The module must be replaced if your Peugeot spare key does not work anymore. This is only done by an Peugeot specialist or expert auto locksmith. Peugeot keys are, unlike other vehicles, are secured by an immobilizer device. This requires the proper coding to start the car. It is for this reason that you should only trust the Peugeot locksmith to design and program the replacement.
Computers with faulty on-board computers
The on-board computer in your Peugeot is responsible many functions in your car including airbags and power windows. The on-board computer displays a code if something goes wrong. The code is stored in the system until the problem is resolved. Usually, this will mean replacing the onboard computer.
One of the most frequent causes of the light coming on is loose or corroded connections within the airbag sensor. This can be caused by wear and tear, ageing or exposure to salt and moisture. This issue must be addressed as soon as you can, as an airbag malfunctioning could pose a risk in the event in the event of an accident.
If you encounter a card not found error on your Peugeot, the key battery inside the key fob might be dead or weak. This will stop the key fob from sending a signal to disable the immobilizer on your vehicle. You can test this by pressing the unlock button on the key fob and then attempting to start your vehicle. If this doesn't work the battery on the key needs to be replaced.