P0336: Crankshaft synchronization is unstable even when pulses exist

P0336 is a crankshaft-position performance diagnostic. Unlike a simple absence check, the cited GM strategy evaluates repeated resynchronization, failure to locate the synchronization gap and incorrect pulse counts. A signal can therefore be present without being usable for position tracking.

Three paths to a performance fault

One path detects eight or more crank resynchronizations within less than four seconds, using airflow and cam-derived speed as prerequisites. Another evaluates a missing synchronization gap: at least 0.4 seconds while running, or 1.5 seconds after starter engagement with supporting evidence of rotation.

The table also includes a revolution-based pulse-count evaluation. Its printed extreme count bounds should not be mistaken for the engine's expected reluctor tooth count. The document does not establish a universal tooth pattern for all vehicles.

Observe synchronization, not only rpm

Record synchronization status and the crank/cam relationship alongside a waveform when the vehicle procedure calls for one. A scan tool showing engine rpm does not prove the reference gap is consistently recognized. P0335 and relevant cam faults can alter which diagnostic path is available.

Verification should show stable synchronization in the previously affected starting or running condition. Merely replacing a position sensor or clearing P0336 does not demonstrate that the missing-gap or repeated-resynchronization behavior has ended. Use the engine-specific pattern specification before judging a waveform or physical reluctor.

Source and applicability

This explanation is limited to the 2025 GM 25OBDG03A monitor on page 266. Its thresholds are calibration examples, not universal specifications. Confirm the vehicle, engine and controller procedure before applying them.