P0328
Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)
Powertrain Ignition System Knock Detection 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

Your knock sensor is sending a weaker-than-normal electrical signal to the engine computer, like a microphone that's turned down too low. This prevents the engine from detecting pinging (detonation) and adjusting timing properly.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Engine pinging or knocking under acceleration
Reduced fuel economy and performance
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Embedded Systems Insight
What the ECU/ECM is actually computing

The knock sensor generates a voltage signal (typically 0.5–5V AC) when it detects vibrations from detonation. The ECM monitors this signal amplitude and frequency. When the signal drops below the minimum threshold, the ECM cannot reliably detect knock and triggers P0328.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Knock Sensor Voltage 0.5–5V AC oscillating signal Below 0.1V or no signal detected
Signal Continuity Continuous during combustion events Open circuit or intermittent connection
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Knock sensor connector and wiring
Inspect for corrosion, water damage, or loose pins at the sensor connector and repair or reseat.
2
Knock sensor harness
Check the wiring loom from sensor to ECM for cracks, pinches, or abrasion that exposes wire.
3
Knock Sensor 1
Replace the sensor itself if connector and wiring are sound; sensor has likely failed internally.