Diagnostic article Generic OBD-II
P032C: knock sensor C low filtered output
P032C is a low-circuit diagnostic for knock sensor 3 in the cited table, corresponding to the catalog’s sensor C label.
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Documented application
2025 GM 25OBDG07A Part2 diagnostic monitor documentation; the application-matrix filename mismatch is unresolved, so no model or engine applicability is inferred.
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.
P032C is a low-circuit diagnostic for knock sensor 3 in the cited table, corresponding to the catalog’s sensor C label. The monitor interprets a low filtered output as short-to-ground evidence rather than measuring excessive combustion knock.
Event count and sampling interval
The threshold is below 0.2 volt with engine speed above 500 rpm. The row specifies three qualifying events and two-trip reporting. It also states that the check runs every 15 to 120 seconds as a function of engine speed and uses a low-pass filter gain of 0.5.
Three events therefore do not mean three seconds. A short observation may fail to include the required repeated diagnostic opportunities, especially at an operating point with a longer interval.
Keep electrical and reference checks separate
The same page lists an open-load test and a reference-signal rationality test under different codes. Those checks use different counters and operating requirements. A normal knock-control response alone does not prove that this particular low-output diagnostic passed.
Verification should establish that the sensor-3 low-circuit test completed with acceptable filtered output at an eligible speed. The table identifies a ground-short pattern but does not specify a pinout or prove whether the sensor, wiring, or interface caused that pattern.
Documentation and applicability
These details describe the monitor in GM’s 2025 25OBDG07A Part2 file. Its application-matrix filename does not match the download index, so model and engine applicability remain unresolved. Use the vehicle’s correct service information before applying these calibration details.
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
Knock/Combustion Vibration Sensor C Circuit Low
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