P0328: Knock/Combustion Vibration Sensor A Circuit High

What does P0328 mean?

The knock sensor is a piezoelectric structure-borne sound sensor bolted to the engine block; the module evaluates its signal per cylinder and retards ignition when it detects knock. Sensor A is the first sensor (bank 1 or a single sensor). With a fault the module retards ignition across the board as protection – noticeable loss of power and higher consumption. P0328 means the diagnostic DC voltage at the sensor input is too high – typically a short to voltage. GM sets it above 39 % of 5 V in 50 of 63 samples, in the first trip; Ford checks actively once every 250 engine cycles on modules with this circuit.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Loss of power, sluggish response from ignition retard
• Higher fuel consumption

Common causes

• High Signal or return wire shorted to voltage
• Medium Corrosion or moisture in the connector
• Medium Sensor faulty internally
• Low Engine module internal

Likelihood is a general estimate across vehicles; your make and model may differ.