Yesterday we travelled back from the campsite towing our caravan. We got back to storage and stopped to empty the loo, on return to the car it wouldn't start and kept flashing "immobiliser malfunction". We had both batteries with us and they had both remained in the car when we'd got out. As we have found changing the batteries usually solves this we changed both fobs with brand new Duracell batteries, still no joy. I went into the caravan to get something and realised that we'd left the Master switch on whilst travelling. We turned it off and disconnected the electrics from the tow bar and the car started immediately. We are constantly changing the batteries every 3/4 weeks. Has anyone any ideas? Is this one problem or two separate problems? thanks.