Diagnostic article Generic OBD-II
P2158: vehicle-speed signal two remains unchanged inside a qualified range
GM P2158 in this historical hybrid example detects an unchanged raw speed signal, rather than the excessive-speed signal check assigned to P2159.
Read before applying this article
Documented application
GM 2009 09OBDG13 2-Mode Hybrid Diagnostics, cited vehicle-speed signal-two inactivity 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.
P2158 is a stuck-signal check for vehicle-speed signal 2 in the cited GM 2009 hybrid table. The controller is looking for an unchanged raw signal. That is a different observation from the high-range speed value evaluated by the adjacent P2159 diagnostic.
The unchanged signal must be qualified
The table lists vehicle speed above 6.215 mph and below 170.9 mph, with an eleven-second unchanged-signal condition. The important point is the raw signal's lack of change under the documented conditions, not an allegation that the vehicle was physically travelling at the upper boundary.
The source does not identify a universal wheel location, sensor connector or raw-data scaling for signal 2. A displayed dashboard speed that appears steady is not automatically equivalent to the internal signal the controller monitors.
Separate a frozen report from a sensor disagreement
Record the signal identity and raw-data behavior available through the correct diagnostic tool. The nearby P215B comparison between two speed signals answers another question: whether their values are plausible together. A stuck record and an inter-signal mismatch should therefore be interpreted separately.
The parameter table supplies no road-test instruction or component replacement rule. A technician must use the applicable vehicle procedure to identify the actual source of signal 2 and determine whether its reporting path is frozen or otherwise faulty. Do not attempt to recreate the printed upper speed boundary; it is a monitor limit, not a safe test target.
Source and applicability
GM 2009 09OBDG13 2-Mode Hybrid Diagnostics, cited vehicle-speed signal-two inactivity 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
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