WARNING
This applies to all Rover 75 and ZT models.
DO NOT continue to try and start the car with a failing battery.
There is a possibility for the transponder chip in the key to become corrupted as it can scramble the rolling code with that stored in the immobiliser.
The engine disabled icon will display on the instument pack and you will no longer be able to start the car using that key.
To reduce the risk of this happening the best course of action is that if your car will not start as normal and the headlamps start to flash
Don't continue to make attempts to start the car until you have charged the battery or replaced it if the battery has failed.
However should you be unfortunate and find that this has happened then any of the club members who offer the replacement key service should be able to re-sync the key with the immobiliser.
Russ