Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code P0328, Knock Sensor Open - "S" & "T" Series 4.3L (VIN Z): Notes
Knock sensor circuit consists of 2 knock sensors connected in parallel and a single wire to control module. Each knock sensor has a resistance value of about 8600 ohms. Control module supplies a 5 volt reference to sensors, but because of sensor resistance, it is cut to about 2.5 volts. When a knock occurs, a small AC voltage is generated by sensors on top of existing 2.5 volts. An AC voltage monitor in control module will detect this voltage and provide a signal to begin retarding spark until knock diminishes.
- Control module applies 5 volts on sensor circuit which should be present at connectors when sensors are disconnected.
- By verifying sensor resistance, problem can be narrowed to connector, sensor installation or control module.
- Improperly installed sensor can prevent sensor from grounding to block.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.