Diagnostic article Generic OBD-II
P2579: Turbo-speed plausibility is a difference test, not overspeed
P2579 compares a turbo-speed signal with a gradient-limited version, while the generic sensor letter has not been mapped to the source’s bank designation.
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Documented application
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability 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.
P2579 is a plausibility check in the cited GM monitor. It compares the current turbo-speed value with a version whose rate of change has been limited. The listed failure is an absolute difference above 250,000 rpm, evaluated with engine speed above 1,000 rpm and a 50 ms interval.
What the comparison means
This is different from asking whether actual turbo speed exceeds a maximum. A rate-limited reference responds differently to abrupt changes; disagreement with it identifies signal behavior that the plausibility check rejects. Do not translate the difference threshold into a normal operating-speed specification.
An informative record keeps the current speed, filtered reference and engine speed together. A single speed value cannot show whether the comparison failed, while a successful observation outside the enable window is not proof of monitor completion.
Bank identity requires review
The generic title identifies sensor A. The GM row labels its compared signal bank 2, while the companion P2594 row names bank 1. The relationship between generic sensor letters and these source-specific bank labels is not established; the naming difference alone does not prove an error. Resolve the actual calibration and sensor mapping before locating hardware; the monitor does not itself prove that the sensor needs replacement.
Document scope and source
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred. These figures explain the cited controller logic, not a vehicle-specific repair instruction. Match the vehicle’s service information before applying them.
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
Turbocharger/Supercharger Speed Sensor A Circuit Range/Performance
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