I have a 59reg 2ltr diesel, every now and then when I'm accelerating normally in 3rd or 4th gear the engine will reduce power,a flashing symbol ( glow plug light) and a message( engine fault workshop) will appear. Also exhaust gas warning light is on. If ignition is turned off it resets itself. I have had diagnostic check but it not showing anything because fault never seems to happen at a time when I can take it to a garage. If anyone has had simular can they please tell me what it was . Thanks