How do you reset immobilizer citroen xsara?

To reset the immobilizer on a Citroën Xsara, first ensure that you have the correct key fob. Insert the key into the ignition and turn it to the "On" position without starting the engine, then leave it for about 10 minutes until the immobilizer light goes off. Turn the key back to the "Off" position, then repeat this process two more times. After the third cycle, try starting the engine with the key. If issues persist, consult a professional or refer to the owner's manual for specific instructions.