DTC P0343: Camshaft Position Sensor Circuit - High: Description

WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.

The camshaft position (CMP) sensor works in conjunction with a 1X reluctor wheel on the camshaft. The PCM provides a 12-volt reference supply to the CMP sensor as well as a low reference and a signal circuit. The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. When the camshaft rotates, the reluctor wheel interrupts a magnetic field that is produced by a magnet within the sensor. The sensor's internal circuitry detects this condition, and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the CKP sensor 24X signal in order to determine the crankshaft position and the stroke. This diagnostic monitors for a loss of a Camshaft Position sensor signal. As long as the PCM receives the CKP sensor 24X signal, the engine will start. The PCM can determine top dead center for all cylinders by using the CKP sensor 24X signal alone. The PCM uses the CMP sensor 1X signal in order to determine if the cylinder at top dead center is on the firing stroke, or on the exhaust stroke. The system attempts synchronization and looks for an increase in the engine speed, indicating that the engine started. If the PCM does not detect an increase in the engine speed, the PCM assumes an incorrect synchronization to the exhaust stroke, and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.