Diagnostic article Generic OBD-II
P0338: Crank tooth-count plausibility in a GM implementation
P0338 is documented as a crank tooth-count rationality check in this GM summary, requiring calibration confirmation.
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Documented application
2009 General Motors diagnostic parameter file 09OBDG02 Engine Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P0338 is broadly described as a high crankshaft-position circuit signal. The GM group 02 table instead presents a rationality check of counted teeth between reference-gap events. This article explains that documented implementation without treating it as the definition for every vehicle.
A signal can exist and still be implausible
A tooth-count comparison evaluates the pattern recognized by the controller, not just the presence of voltage. The source places it beside separate checks for a missing reference gap, unexpected resynchronization and intermittent loss of engine-speed information. Those distinctions help explain why a sensor can appear active while synchronization remains unreliable.
The neighboring checks should not be merged into a single replacement rule. A code combination and the actual recognized pattern provide more diagnostic context than the generic word high.
Confirm the calibration before using numerical limits
The printed tooth-count criterion is not suitable here for a general workshop tolerance. Its applicability and the relationship to the generic circuit-high label need confirmation in the vehicle's service procedure. No connector voltage, sensor gap or replacement part is established by this summary.
Preserve reference-gap and synchronization information where the diagnostic equipment exposes it, alongside companion crank and cam faults. Verification should demonstrate stable recognized timing information and successful completion of the relevant check. Clearing P0338 or observing engine speed momentarily does not establish that the pattern fault has been corrected.
Source and applicability
2009 General Motors diagnostic parameter file 09OBDG02 Engine Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established. This explanation describes the documented monitor, not a universal repair procedure.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Crankshaft Position Sensor A Circuit High
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT