Diagnostic article Generic OBD-II
P08A1: The second Y-position channel is judged on raw low-duty evidence
Understand GM P08A1 and why selector sensor identity, Y-axis duty cycle and wakeup timing all matter to the low-circuit result.
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Documented application
2025 GM 03B documented monitor only. Vehicle, engine and controller calibration applicability must be established separately; no model fitment is inferred from the file.
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.
P08A1 identifies the low-circuit result for gear-lever Y position sensor 2. In this GM implementation, the controller assesses the raw duty cycle on that particular input. It does not establish a physical lever position from the word low.
Separate the signal boundary from the enable delay
The failure threshold is duty cycle below five percent. Monitoring requires the controller to have been awake for at least 0.05 second. The strategy then counts ten failing samples within twelve on a 25-millisecond loop, with two-trip reporting.
A signal transition during initialization and repeated low duty after enablement are therefore different observations. Preserve time since wakeup alongside the sample sequence rather than interpreting every momentary low percentage as the recorded fault.
A different selector channel cannot verify this one
Sensor 2's Y signal must remain identifiable in the data. A healthy X signal or an acceptable first-sensor reading does not demonstrate that this channel passed. A plausible decoded gear display also cannot replace the underlying electrical-range evidence.
The source gives neither a duty-to-position map nor a conversion to an external connector voltage. It supports investigating the specified low-duty signal without asserting that a gear has disengaged or a selector mechanism is jammed. The applicable circuit procedure is needed to distinguish the sensor, connection and receiving-controller possibilities before choosing a repair.
Source and applicability
2025 GM 03B documented monitor only. Vehicle, engine and controller calibration applicability must be established separately; no model fitment is inferred from the file. GM PDF, physical page 616.
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
Gear Lever Y Position Sensor 2 Circuit Low
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