Diagnostic article Generic OBD-II
P2548: Performance-launch torque message fails an integrity check
Understand the message protection and rolling-counter checks behind this GM P2548 torque-request fault.
Read before applying this article
Documented application
GM 2009 09OBDG07 Engine Diagnostics, expressly LSA-only performance-launch torque request monitor. No broader engine, model or manufacturer applicability is claimed.
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.
P2548 is a torque-management request input B fault. In the cited GM LSA-only monitor, that input is a performance-launch torque request carried in serial message $1C8. The controller is checking whether the received request is valid; it is not measuring a torque sensor or proving an engine cannot produce commanded torque.
Two checks protect the request
One branch verifies the message's protection relationship using a two's-complement check. It requires ten protection errors out of ten samples. The other verifies that the rolling count advances from the previous message by one and fails at three rolling-count errors out of ten samples.
These branches answer different questions: whether a message's protected content is consistent, and whether its sequence advances as expected. Their distinct thresholds matter when interpreting intermittent communication evidence. The source does not say that either outcome automatically identifies the sending module as defective.
Preserve network context
The monitor needs the run/crank state active for more than 0.50 seconds and an enabled diagnostic. It operates at a 100-millisecond interval and uses a one-trip Special Type C classification in this table.
Record companion communication faults, request status and the operating event before clearing the code. A static torque value that looks plausible afterward does not demonstrate that protection and sequence checks passed during the original event. Verification concerns a valid message stream under the applicable conditions, not a high-load road test. The source's LSA-only restriction must be retained; it does not support applying this exact message strategy to every vehicle with the generic P2548 label.
Source and applicability
GM 2009 09OBDG07 Engine Diagnostics, expressly LSA-only performance-launch torque request monitor. No broader engine, model or manufacturer applicability is claimed.
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
Torque Management Request Input Signal B
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