My Kia Picanto has developed an intermittent starting problem. It has had two new crankshaft sensors in the last six months. The sensor was initially replaced after the car wouldn't start at all. Checks by the roadside mechanic ruled out fuel and electrics and narrowed it down to the crankshaft sensor. The symptoms are intermittent but the car is now unreliable as you never know whether it will start. It occurs when the engine is cold, hot, dry or wet. Any ideas?