I am a Jaguar not with 10 of them including an XJS coupe 6.0 which, without warning, seems to run on only one bank (6 cylinders) then a red ENGINE light appears and the car 'switches' to full power and runs without any problem , except the light stays on the dash !
Turn off ignition and the light disappears, until the next time. The warning light appears at no particular time other than usually when the engine is fairly cold.

FRUSTRATION ! Please help !