mal young

hi there fellow lexus owners i have just got my 1st is 220d on an 06 plate 3 weeks ago and it was running superb until today when i lost all power. there was no msg or error on the dash but once i pulled up and re started the engine is was fine again for 5 mins then lost power again what could this be ?. sorry im a complete newby on this site so please bare with me thanks in advance for any info guys.