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Difficulty
Credit
evilution
Mod ID
679
Cost
For
450 Fortwo 600cc
450 Fortwo 700cc
452 Roadster 700cc
450 Fortwo 700cc
452 Roadster 700cc
If the indicators flash 9 times it means there is a fault with the key.
It can be 1 of 2 faults, 1 is OK, the other isn't good.
If you press unlock on the key and the indicators flash 9 times, the doors open and you can
start the car then the battery in the keyfob is running low and should be
If you press unlock on the key and the indicators flash 9 times but the doors don't unlock
then you have problems. Even if you get in through the boot and open the doors, the
immobiliser will not be disabled so the car won't start.
The only way to fix this fault is to start the car with your spare key and take the car to a smart
dealer or a smart specialist. They will either recode the car to the old key or code a new one.
Then you are an idiot for not getting a second key. The smart system can have
4 keys coded to it and the car comes from the factory with 2 keys as standard.
Then you only have yourself to blame, you waiting too long. Now you'll
have to trailer your car to your nearest smart dealer and have it sorted.
You'll have to have it trailered hundreds of miles, simple.
You'd better find someone with a TAN code calculator and an MB-Star machine or
your car isn't moving. Shouldn't have bought a car in a country with no dealer backup.
I wouldn't put it here even if you could but anyway, it can't be done.
No there isn't.
Sometimes you can use the old key, sometimes not, it depends on why it failed.
So far, the only reason for the 9 indicator flashes on this model is a low battery in the key fob.
Change the battery inside your keyfob and you should be good to go.
If you have a US smart fortwo, the 9 flashes will also combine with excessive chirping from the alarm.
The reason that the 451 keys don't have the same desyncing issues as the 450 and Roadster is that
they have 2 totally different types of immobiliser. The 450 and Roadster immobiliser is deactivated by the
keyfob whereas the 451 has a more conventional RFID chip and a reader aerial around the ignition barrel.
There are plenty of rumours. Faulty immobilser coding, faulty rolling code generation, key
damaged, battery flat for too long inside the key, buttons pressed whilst not near the car.
None of them really hold much truth from what I can see. I think the issue is with lead free solder.
Companies started using lead free solder many years ago to please enviromentalists. The problem is, lead free
solder isn't very good. Firstly it cracks due to it being far more rigid than lead solder. This is no good as keys
can take quite a knock over their lifetime. A crack causes a poor connection and everything goes wrong.
Secondly is a problem called "tin whiskers". It was these hair-like growths from the solder that
originally caused lead solder to be made. The addition of lead stops these growths from occurring.
I have highlighted a few but if you look closely, you'll see many more. It only takes 1 tin whisker to grow
and touch another component to create a short circuit and put the key out of sync when a button is pressed.
Every year, I'd recommend brushing the component face of the key PCB with a dry toothbrush.
This will break any tin whisker growth. Blow the circuit board clean before closing the key back up.
