P0324: Excessive filtered knock intensity, including false knock

P0324 is described here as a knock-sensor performance check on a per-cylinder basis. The GM monitor evaluates excessive knock intensity, and the source expressly includes both real and false knock. The code therefore does not prove combustion detonation by itself.

What intensity means in this strategy

The controller forms an intensity value from the current knock event relative to its knock threshold. Negative values are limited to zero, while positive values represent event magnitude above the threshold. A first-order filter then smooths this information before comparison with a calibrated excessive-knock limit.

The table gives a filter weighting coefficient of 0.0600 and updates it each engine event. A single spike is not the same as a persistently high filtered value. The threshold itself is in a supporting table, not a universal sensor-voltage limit.

Operating context changes interpretation

The test requires more than two seconds of runtime and over 100 accumulated engine revolutions above the minimum speed. It also defines speed, air-per-cylinder and temperature eligibility. Capture the affected operating region and any available per-cylinder intensity information.

A focused investigation must separate real combustion-related knock from a signal representing other vibration. The page does not identify a fuel grade, mechanical part or sensor replacement as the solution. Verify that the filtered monitor result passes under comparable eligible conditions after the actual cause is established.

Source and applicability

This explanation is limited to the 2025 GM 25OBDG03A monitor on page 258. Its thresholds are calibration examples, not universal specifications. Confirm the vehicle, engine and controller procedure before applying them.