Diagnostic article Generic OBD-II
P263B: The MIL output remains high during an on command
See how P263B uses on-state driver feedback and a four-of-five sample decision to classify the MIL circuit.
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Documented application
2025 GM 25OBDG06A 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.
P263B evaluates the malfunction-indicator lamp control circuit while the output driver is commanded on. In the described GM implementation, a high signal in that state supports a short-to-power classification. The high designation is electrical; it does not mean that the lamp is unusually bright or that an engine parameter is excessive.
Command state changes the meaning of voltage
The companion low-circuit monitor P263A observes the driver-off state. Applying that interpretation to an on-state reading would confuse two different checks. Record the controller’s command together with the signal being evaluated.
For P263B, four failures out of five samples are required, with a 50 ms sample interval. The monitor also requires run/crank voltage above 11 V and remote vehicle start not active. A single transient during a different operating state does not reproduce the stated confirmation logic.
Keep the fault local to its evidence
The table identifies a lamp-control electrical problem and does not promise a particular visible lamp state. The indicator itself is part of the circuit under suspicion, so its appearance should not replace controller evidence.
Verification needs the matching wiring and driver procedure, including the correct interpretation of the on command. The source does not locate the shorted path, identify a failed output stage, or justify replacing an entire control module. It also does not diagnose the emissions fault that the lamp may separately be intended to display.
Source and applicability
2025 GM 25OBDG06A 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. 25OBDG06A, PDF page 553. 25OBDG06A, PDF page 554.
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
MIL Control 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