Smart Brabus Roadster Coupe won't lock

[mellasdad]

Cars been SORN since November but just re registered but find that having got everything up and running, I can't lock it! Pressing the key fob, the doors lock but then immediately unlock.
This is annoying as it means I con't go anywhere in it as the alarm goes off!

Any suggestions please?

[E-bmw]

Most cars will immediately unlock if one of its sensors is saying it isn't closed.

Could be boot/bonnet or door obviously.

[GreenV8S]

I guess it thinks one of the doors is open, or is failing to lock via the central locking - maybe because the lock is stiff through lack of use.
A bit of oil on each lock, and some time locking and unlocking it to ease the mechanism may solve the problem. Failing that, can you lock all doors except the driver's from the inside and then lock the last one with the key?

[LimSlip]

Does it lock correctly if you get in the car and press the lock button on the dashboard? If so this points to a problem with the rear hatch lock sensor, there is a wire going to the SAM that gets grounded when the hatch is closed which can fail, probably due to water ingress.

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