P032B: Knock-sensor C performance uses a normalized reference level

P032B is the range/performance code for knock sensor C. In the cited GM table the channel is called sensor 3, and the check evaluates a normalized knock-control reference level. This is a signal-rationality assessment, not a direct declaration of damaging combustion knock.

A mapped reference and a persistence counter

The high reference boundary varies from 0.67109 to 2.5 volt-milliseconds according to a lookup table. Those units and the mapped range matter: the value cannot be treated as an instantaneous sensor-voltage specification.

The diagnostic debounce counter must exceed 30 counts. The row also lists a 0.1-second check interval and two-trip reporting. These are distinct timing concepts; the short interval does not eliminate the counter requirement.

Control eligibility shapes the result

Engine coolant temperature at startup must exceed 34.96°C, and knock control must be active. The surrounding enable logic also considers load and dynamic conditions. A cold-start or inactive-control observation is therefore not equivalent to a completed reference-level assessment.

Preserve the channel identity, reference-level parameter and control state when reviewing the fault. A raw vibration trace by itself may not represent the normalized quantity being evaluated. The table does not identify a failed sensor mounting, harness or controller component. Confirm sensor mapping and the complete calibration procedure before interpreting the mapped boundary or deciding what hardware requires service.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 601; GM diagnostic table, PDF page 602.