Diagnostic article Generic OBD-II
P2159: signal-two speed is outside its documented upper range
GM P2159 evaluates an excessive reported speed value, distinct from the unchanged-signal monitor and the two-signal plausibility comparison.
Read before applying this article
Documented application
GM 2009 09OBDG13 2-Mode Hybrid Diagnostics, cited vehicle-speed signal-two range example only. Per-code vehicle, engine and calibration applicability has not been established; use the matching vehicle procedure.
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.
P2159 is the range check for vehicle-speed signal 2 in this GM 2009 example. The monitored event is a reported speed beyond the calibrated upper boundary. It does not by itself establish that the vehicle physically reached that speed.
A range fault is different from a frozen value
The table gives a value above 170.9 mph for three seconds as the range-failure condition. P2158, by contrast, evaluates an unchanged raw signal within a specified operating range. A frozen but in-range signal and an excessive reported value are therefore not the same diagnostic event.
The document also assigns a separate code to disagreement between speed signals 1 and 2. That comparison should not be used as a substitute for P2159's own high-range criterion, even if related records are present together.
Identify the report before diagnosing hardware
A technician should preserve the exact speed-channel identity, controller and event data. The parameter sheet does not map signal 2 to a universal wheel sensor or provide a connector pinout. The appropriate vehicle documentation must establish where the reported information originates.
The code does not alone prove a defective sensor, tone wheel or communication module. It supplies a range observation that needs further circuit and data-path diagnosis. No high-speed road test is implied: the numerical boundary is a controller plausibility limit, not a recommended speed or a safe method for reproducing the fault.
Source and applicability
GM 2009 09OBDG13 2-Mode Hybrid Diagnostics, cited vehicle-speed signal-two range example only. Per-code vehicle, engine and calibration applicability has not been established; use the matching vehicle 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
Vehicle Speed Sensor B 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