They say lightning doesnt strike twice - Well believe me it does. My Key fob has stopped working on my E200 hence arming the immobiliser.(I have changed the batteries - Still no good) This happenend to me few years back and I ended up buying a new keyfob from the main dealer pretty expensive at the time few hundred I do recall. I have taken the key fob case apart to have a peep at the pcb and there is no signs of anything loose so I dont believe there is an easy DIY fix. What I would be interseted to Know is - Is there any way of disarming the immobiliser - If I could get the car started I Would use the flip key to open door/boot etc and not bother with FOB ? Also - I see there a Key Fobs for sale on ebay obviously the key blade would have to be changed but would there be a problem programming the key ?