All the symptoms of a flat battery? Starts one day and won't the next? Won't start after a journey? Our 1997 2.0 Megane had these problems. The solution was to clean the TDC sensor which is located on the top of the casing where the gearbox joins the engine. Black plastic angled part on a flat metal bracket held on with two 10mm bolts. Just disconnect the wires, remove the front bolt, loosen the back bolt and tilt it to reveal the tip for cleaning. Be careful not to lose the rubber seal down the back of the engine. Ten minute job! Good luck.