UK Car Repair: Renault Starting Problems, renault megane, obd 2

Question
I have a W Plate Renault Megane that has intermittent starting problems. when the engine is cold it starts no problem. but after running for bout 15/20 mins it will start intermittently. If the engine doesn't start i won't for about 25/30mins. ..  

Answer
What year is the car? If it has an OBD 2 system you may have to scan it to see if it shows a fault. The problem seems to be only when the engine is hot. It could be a faulty water temprature sensor,as it heats up, it disconnects the cold start system. Of course it may be a bad connection that is affected by heat. Quite difficult to say exactly. When the fault occurs you need to check for an ignition spark, if it is OK you then have to check fuel delivery in order to get an idea of where to begin. is clrearly working is