I have came across a nasty problem two weeks ago. I was driving on M1 to London and my car just choked and the service light came on the display. nothing else the car has power and no problems.
On the services the AA discovered that there was a misfire on the 1st cylinder. I was advised to change the coil pack and spark plugs.
After trying to find the parts on Sunday (Siemens Coil pack NGK spark plugs) and replaced them everything was ok until I hit the motorway again.
I have noticed now that the car is behaving without any problems if used in the city mode, unless I am accelerating (not always) very hard.
On the motorway it comes when the car is driven with a constant speed (60-75MPH).
The light goes off if i switch the engine off.
About 6 moths ago i was called to Vx dealer to replace fuel pressure regulator.
Car has 51k miles on the clock and it was looked after.
Any ideas about what to check?
Is there a friendly forum user with computer to check the code faults in Coventry?