Diagnostic article Generic OBD-II
P2C0A: Hall sensor B can report a valid-looking sequence at the wrong time
Learn how P2C0A detects an intake profile shift without a corresponding command and why final position alone is insufficient.
Read before applying this article
Documented application
2025 GM 25OBDG03B documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred.
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.
P2C0A evaluates intake profile-position sensor B, described as Hall sensor 2 in the GM table. The concern is not simply a missing signal. The controller sees a sequence consistent with profile-pin movement even though it did not request that shift.
A complete sequence can still be implausible
The monitored feedback passes through extending, extended and retracted states. Ending in the expected retracted state does not make the preceding uncommanded event legitimate. This is why preserving only the last position value can lose the useful evidence.
The source’s internal state thresholds have no clear physical unit on this page. They describe the controller’s state recognition, not a transferable voltage or travel test. Command history remains the key context for interpreting the sequence.
Confirm the engine references are usable
The monitor needs a running engine, supply above 11 V and no relevant active crank or intake/exhaust cam-sensor faults. A failed timing reference would weaken the basis for placing the Hall transitions in the correct engine-cycle context.
Four failure readings out of five are required. Useful investigation keeps the B-channel transitions, shift request and reference-signal status together. The code does not distinguish physical uncommanded pin movement from a misleading Hall signal by itself. The correct procedure must determine which interpretation matches the actual vehicle before any sensor or actuator is replaced.
Source and applicability
2025 GM 25OBDG03B documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred. These criteria explain controller logic, not a complete repair procedure. 25OBDG03B, PDF page 902.
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
A Camshaft Profile Actuator Position Sensor B Range/Performance Bank 1
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