A P0340 error code in a 2002 Mitsubishi Lancer means that there is a problem in either a camshaft position sensor, the starter, or there is a weak or dead battery. If the car does not start, has less power or does not turn on accessories, then this code appears.
If the car starts and turns on accessories without the need of a jump, then the problem lies with the camshaft position sensor. This should be taken to the shop immediately or damage to the engine could occur. If the car does not start without a jump, then the problem exists within the battery, and the owner can easily replace the battery. If the car does not start even with a jump, then the problem lies with the starter, and the car should be taken to a mechanic to have the starter replaced.