P2581: What a high turbo-speed line means when pulses stop changing

The P2581 row identifies a bank-one turbo-speed input that remains high while both its pulse-time difference and pulse-number difference are zero. The combined condition separates a static high line from the high portion of a normal pulse train.

Look beyond the displayed rpm

GM requires at least 50 counts of that condition, engine speed above 1,500 rpm and battery voltage of at least 9 V. The row also requires the boost-control-active flag to be false. A captured high logic state without the pulse history or enable context is insufficient evidence for this particular monitor.

Its timing column shows 655350 ms, an unusually large value whose calibration meaning is unresolved here. This article does not turn that figure into a prescribed waiting time. The source-review flag applies to that timing detail, not to a fabricated alternative threshold.

What to verify next

Use the applicable service information to establish the signal channel and expected pulse behavior. Record whether the input actually remains high across successive observations and whether the pulse counters change. The code classifies the input behavior; it does not independently identify a failed speed sensor or authorize a universal replacement procedure.

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.

GM physical PDF page 883.