P0342: A low intake-cam signal means missing edges as the crank turns

P0342 concerns a low signal from the bank 1 intake camshaft sensor. The GM monitor combines two observations: the crankshaft continues to turn, but new camshaft signal edges are not detected and the signal remains low.

Rotation supplies the expectation

The row requires at least four crankshaft revolutions. A recognized crank signal with its gap pattern must be present, ignition must be on, and backward rotation must not be detected. The controller therefore has a basis for expecting camshaft edges before declaring their absence.

A stationary engine with a low cam signal is not the same condition. The relevant observation is the signal level at the transition into a no-signal state while the qualifying crank rotation is occurring.

Distinguish missing edges from correlation

A correlation code compares the relative timing of usable crank and cam signals. P0342 here instead concerns a cam input that supplies no new edges and remains low. That distinction changes what evidence a waveform or scan capture must show.

Retain crank synchronization, rotation state and the cam input level together. The source uses one-trip reporting and refers to enable and inhibit tables, but it does not identify the cause of the missing edges. The sensor, its supply and signal path require the applicable vehicle procedure; replacing the sensor solely from the low label skips that localization.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 589; GM diagnostic table, PDF page 590.