It should not show “off” when the engine is running.
When the engine is being assembled, there should be two camshaft sensor pulse signals for each revolution of the left camshaft pulley (which rotates at half the speed of the camshaft). Because the pulley is turning relatively slowly, the crankshaft’s on/off signal, which is based on pulses, will cycle on and off due to the longer time between pulses. But once the engine is running, the rate at which the camshaft sensor pulses reach the ECM is higher and the camshaft off/on status remains “on”.
P0340 is related to a short or open circuit in the camshaft position sensor wiring, or in the sensor itself. The code is set as soon as the error detection criteria are met. In this direction, there should be two camshaft position sensor pulses for every two revolutions of the crankshaft. If this is not the case, that is, there are more or less pulses measured in a total of 8 revolutions of the crankshaft, the code is set.
The FSM troubleshooting guide for the code focuses on the wiring, looking at both the continuity between the sensor and the ECM and the existence of shorts to ground on both wires. Either fault can affect the number of pulses reaching the ECM.
