Thanks for all the responses. I’m fairly certain that there are no seat sensors. I have a pair of wires going into each seat - two pairs of power wires for the heated seats back and base.
I don’t believe it is a BMW system as my code reader will talk to the air bag system on our 2003 e46. It may however be a BMW Morgan hybrid system.
I think it is likely to be a loose connection generating excess resistance I just need to find and check all the connections.
