try the code 7241
First of all you can check to see if the plip key is sending a signal by using the camera on your phone ,just point the plip at you camera phone and press the plip if you see a white light , the plip is sending a signal if not then you need to resolder the transmitter diode back onto the circuit board then see if the plip works ,if the plip is not working after that,it's possible that the plip is now faulty, now you can still start the engine if the plip does not work , but you will need the 4 digit immobilser code , try asking for the code on this site, someone might be able to get it for you , but you might have to give your chassi number for them to get the code, when you have the code the way to enter te code is by using the central locking button, this is how it is done , switch the ignition on ,say for example your code is 1234, then you press and hold the central locking button untill you see the red led flash once on the instrument panel, then let go ,then press it again and hold it untill you have counted 2 flashers of the red led , then let go of the switch, then press the button and hold it untill you have counted 3 flashers,then let go ,do the same for the 4th digit , and if you have entered the code correctly the red led should stay on ,and if it does just start the engine, ,but if you switch the ignition of and leave it for more than 1 min you will have to enter the code again ,so you can start the engine and you will have to do this each time you leave the car ,
from a renault website