[Roverlike]

First thing I would suggest is to check if you have some broken wires at boot hinge folding area: MG F/TF Boot Hinge/Lid Wiring Loom Inspection Guide since earth point which correspond with those wires which might break and touching each other is also erthing point of engine ecu

 

[Roverlike]

Way to make a check is to take the plug and one end of multimeter terminal to earth pin and with other terminal check each other pins to see if you have connectivity. This way you ight find which wire or pin produces this error. It is possible that some small piece of loose wire is touching another pin on connector itself.