well firs o all u need o noe that it appears in awl cars wen ur cars ignition is in switch mode, and goes wen the car is started,, thats not a problem its normal,,
but if cumes wen the car is started thats a problem.
it appears when there is sum sort of a wiring issue.. i had it in my car, the c.n.g people had cutted the calm shaft sensor wire,, but it can only be known by conecting a OBD device, secondly the computer showd a faulty sensor, but actualy the wire was cut, so before buying anything check the wiring, coz i bought the sensor and on checking with a testor ve got to noe there was no current in it, thankfully i hadnt opened the packet of the sensor,,,