If it helps my scan tool does not give a solution for that number regarding Aston Martin , the ford response is injector circ cylinder and interm... Don't know if that helps but I do know there are some ford electronics and control devices on my 2000 vantage,, nothing in my service manual for that , there is an example in the shop manual utilizing the OBDII scan tool and coincidentally uses p1243 as its example. The previous screen shows the operator selecting emission control trouble codes and then p1243 as the found error, seems like it would be related to an emissions control sensor,, hope that helps