P0725: A hardware-reported engine-speed circuit fault differs from implausible speed

P0725 identifies an engine-speed input circuit problem. In this GM transmission-controller example, the decisive input is the speed-sensor circuit hardware monitor reporting a fault. That is different evidence from simply observing an unusual engine-speed number on a scan display.

The hardware status must persist

The source requires the hardware monitor to remain in its fault state for two seconds. The diagnostic task runs at a 20-millisecond frequency and uses two-trip reporting. A single brief anomaly is therefore not equivalent to the persistent hardware status described here.

The table also lists the relevant not-failed-this-key-on state as an enable. This means diagnostic history is part of the operating context; repeated observations after the test has already failed need not represent independent new test opportunities.

Compare status with the speed signal, not in place of it

Retain the hardware fault indication and its duration alongside the reported engine speed. An apparently reasonable speed value at one instant cannot independently prove that the circuit monitor stayed healthy through the qualifying interval. Conversely, a changing or noisy speed display does not by itself establish that this particular hardware-status condition occurred.

The code does not locate a physical engine-speed sensor or prove that a transmission controller needs replacement. The source provides no connector terminals or waveform thresholds for a direct circuit test. Establish the exact speed-input architecture and use its applicable service procedure to identify where the reported circuit failure arises.

Source and applicability

2025 GM 06B documented monitor only. Vehicle, engine and controller calibration applicability must be established separately; no model fitment is inferred from the file. GM PDF, physical page 743.