P0346: Bank 2 intake-cam performance checks the signal pattern

P0346 is a range/performance code for the bank 2 intake camshaft signal. The GM implementation examines whether the acquired pattern matches the expected reference. A signal can contain electrical transitions and still fail this rationality check.

Several pattern defects share the code

The table lists incorrect segment length, failure to match the signal and reference tables, an incorrect sequence of entries, or excessive erroneous edge positions. These alternatives explain why a simple “signal present” observation cannot demonstrate that the pattern is valid.

The defect counter is qualified over crankshaft revolutions. Ignition must be on, a crankshaft gap signal must be recognized, and backward rotation must not be detected. The monitor depends on a usable rotational reference for judging the cam pattern.

Preserve shape and order, not just voltage

A useful waveform assessment retains the order and spacing of cam edges alongside the crank reference. Counting only a few transitions or looking at an average voltage loses the features that this monitor evaluates.

The strategy prose includes an awkward reference to implausible crankshaft operation while identifying the actual inspected channel as bank 2 intake camshaft. The verified criteria concern cam-pattern matching; they do not independently diagnose the crank sensor or mechanical timing. Use the proper reference waveform and service procedure to determine why the pattern differs before replacing a component.

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 591.