Possible Causes

WARNING: This page is about a different car, the 2002 Nissan Pathfinder and 2002 Infiniti QX4. However, it is still accessible from the selected car via links, so may be relevant.

ECM illuminates MIL and sets DTC P0340 when:

Malfunction A

Cylinder No. Signal is not sent to ECM for the first few seconds during engine cranking.

Malfunction B

Cylinder No. Signal is not sent to ECM during engine running.

Malfunction C

Cylinder No. Signal is not in the normal pattern during engine running.

Possible causes are:

CMP sensor (PHASE) circuit is open or shorted.
Poor, loose, corroded or damaged terminal connections.
Defective CMP sensor (PHASE).
Defective intake camshaft.
Defective starter motor.
Faulty starting system circuit.
Dead (weak) battery.