So today I had a bit of a puzzling problem with my car which ultimately had a very mundane solution. It took me longer than it probably should have to find the answer and I didn't find an answer online with my brief search so I have decided to document it here.
I hope this helps anyone searching for a similar problem in the future.
After nipping out to the shops to grab some items, I arrived back at the house, got out as normal and pushed the lock button on the car keyfob.
The car doors initially locked, then IMMEDIATELY unlocked again.
I tried this several times and each time the car doors would just not stay locked.
I tried using the button on the central console and the same thing happened (this told me it was definitely not a fob fault).
I had a quick search online and did find a work around solution:
Press and hold the lock button on the central console for 5 seconds.
The doors do the lock/unlock thing however after 5 seconds, the doors remain locked.
This is intended to be used as a method of locking all the doors if the fob button does not work at all.
While not entirely satisfied, it did give me some peace of mind to allow me to leave the car while I had a better search on the laptop. This search did not provide anything useful.
I eventually gave up and decided I would take it to the dealers to see if they had any ideas. As I set off and started driving down the road, the 'door open' alarm activated.
Turns out that the sensor for the boot was not showing as closed. Gave it a bit of exercise and the door open warning turned off.
Once all the doors were showing closed, all doors locked and stayed locked.
I hadn't spotted this earlier because, well, I was not sitting in the car when using the fob and I had the driver door open, so was expecting to see it activated.
Annoyingly the boot is not part of the central locking system and requires a manual pull cable to unlock. Though I suppose it is good that it sort of warned me that I was about to walk away from the car with the boot 'unlocked'.
Dacia Sandero, 2012Go Top