P0335: Crankshaft pulses missing during cranking or running

P0335 is the crankshaft-position Sensor A circuit diagnostic. The cited GM strategy looks for missing crankshaft pulses and uses different timing when the starter is engaged versus when the engine is running.

Evidence that the engine should be moving

During cranking, the table allows a failure after at least four seconds without a crank pulse when cam pulses or valid airflow evidence indicate rotation. During running with the starter disengaged, a separate path uses a 0.3-second absence. It also lists a revolution-based two-of-ten sample path with cam-sensor prerequisites.

These distinctions matter when a vehicle is difficult to start. No crankshaft pulses while the engine is not actually turning is different from missing pulses while another input confirms rotation. Starter status and corroborating cam/airflow data help establish which path is relevant.

Preserve the missing-signal context

Capture engine-speed data, starter state, cam-pulse status and associated faults. A recovered signal after the event does not identify whether the earlier interruption was at the sensor, connection, wiring or controller input.

The source describes pulse absence rather than a universal supply voltage or sensor resistance. Follow the applicable circuit and waveform procedure to localize the fault. Verification should cover the state in which the signal disappeared—cranking, running or both—and confirm an eligible passing monitor. A successful restart alone may not reproduce a running-only interruption.

Source and applicability

This explanation is limited to the 2025 GM 25OBDG03A monitor on page 265. Its thresholds are calibration examples, not universal specifications. Confirm the vehicle, engine and controller procedure before applying them.