P0332: Knock sensor B low is based on filtered output

P0332 concerns a low signal in the knock-sensor B circuit. GM’s example calls this a sensor 2 short-to-ground check and evaluates filtered output voltage. The word “filtered” matters because the controller’s diagnostic value need not match every instantaneous pulse seen in a raw waveform.

A low boundary with event qualification

The row specifies filtered output below 0.2 volt with engine speed above 500 rpm. It requires three events and uses two-trip reporting. The monitoring schedule is stated as every 15–120 seconds depending on speed, so three events are not automatically three seconds.

The table also references a low-pass filter in the diagnostic integration. It does not provide a universal unplugged-sensor resistance test or a connector pin voltage under every operating state.

Keep the evidence electrical

A quiet-sounding engine cannot disprove this circuit result, because the check is not a listening test for real knock. Preserve the reported channel, the eligible speed condition and evidence that the monitor completed.

A low filtered value does not establish where the grounding condition originates. The sensor, its connections and the controller-side path need the matching vehicle’s circuit procedure to be distinguished. Confirm how sensor 2 maps to the engine before taking measurements. The useful conclusion is a qualified low-output report, not an automatic instruction to replace the knock sensor or alter ignition timing.

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 603.