P0328 - Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor)

P0328 is set when the Engine Control Module (ECM) detects an abnormally high voltage signal (typically exceeding 4.5V) from the knock sensor 1 circuit on bank 1. The knock sensor is a piezoelectric sensor that converts engine block vibrations into an AC voltage signal. The ECM uses this data to detect pre-ignition (knocking) and retard ignition timing accordingly. A high input signal usually indicates an open circuit, a short to voltage in the wiring harness, or an internal sensor failure. When active, the ECM will often default to a 'safe' ignition map with retarded timing to prevent engine damage.