immobilizer problems

[jimbo fr]

Can anyone help , are there any tricks to the immobilizer , was having problems with key fob , had to keep it depressed longer to get it to work , thought it was the batteries so changed them which seemed to fix the problem but 3 hours later it the fob or the immobilizer has totally stopped working and is now the car ( chimaera 500 1998)is stranded . My question can these things be reset or do I have a bigger problem , thanks in advance if you have any ideas . Jim.