my Fob doesnt work any more so im tring to buy a new FOB for it like this one 
but the thing is the frequenty is 433mhz mine is 13560 mhz. It got the same pcf7946 chip, so if i change the pfc chip and the frequenty chip with my old one would that work? because the whole layout looks like the fob i have
The cristal actualy ajusts the internal comunication clock of the device and doesen't have anything to do with the frequency at which the key comunicates with the car. In order for it to know what 433mhz is, it needs a cristal which vibrates in this case at 13560mhz. In other words it knows to divide the 433mhz into the 13560mhz.
The most important things in a car key are the imobilizer chip and and the one that comes programed for unlocking and locking the car.
Be shure to get the same layout board if you plan to move chips. It will be less work if you do.
Thank you for the feedback so its worth a try to buy the one in the picture because the layout is the same like my defect old one.
