If you have any unnecesary beeps after you lock or unlock the car this will help you identify which sensor might be at fault.

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Upon activating the alarm,the LED flashes as follows:

8Hz 2.5s Door/bonnet/boot left open
On 2.5s Faulty ultrasonic sensors
16Hz 2.5s Control unit fault
Off LED fault

Upon deactivation:

1 flash RH front door
2 flashes LH front door
3 flashes RH rear door
4 flashes LH rear door
5 flashes Ultrasonic sensors
6 flashes Bonnet
7 flashes Boot
8 flashes Key operated supply cut off
9 flashes Battery supply cut off
10 flashes 3 or more simultaneous alarms

You can also do a manual diagnosis as follows:

Open the bonnet and turn the ignition key from Marcia to Stop.

Within 15 seconds press the bonnet pin switch 7 times in less than 10 seconds.

You will hear 5 beeps and after 10 seconds the indicators will flash once.

The ultrasonics are now tested, if OK the indicators will flash 3 times and you will hear 3 beeps.

Now you can trigger each sensor in turn (doors/boot/bonnet)and if Ok each trigger will give a beep and a flash.

Turn the key to Marcia and you get a brief siren and the indicators will flash for 2.5 seconds. This operation will automatically exit the test mode, but you can also exit at any point by not triggering any sensor for 30 seconds, at which point the indicators will turn on for 2.5 seconds and a beep will sound.