P0328 – Knock Sensor 1 Circuit High Bank 1 or Single Sensor

P0328 – Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor) means the engine control unit has detected a knock sensor signal that is higher than the expected voltage range. This knock sensor monitors engine vibration to detect detonation and protect the engine by adjusting ignition timing. A high input usually indicates a wiring fault, connector issue, or overly sensitive sensor output. This guide explains what P0328 means, the symptoms, causes, step-by-step diagnostics, and the most effective repair solutions.

What Does P0328 Mean?

P0328 is a generic OBD-II powertrain code indicating that Knock Sensor 1 on Bank 1 — or the only knock sensor on engines with a single sensor — is sending a voltage signal higher than what the ECU considers normal. When the sensor signal spikes or stays abnormally high, the ECU interprets this as an electrical malfunction or severe engine knock, even if none is occurring.

As a safety precaution, the ECU usually retards ignition timing to prevent potential engine damage, which can significantly reduce performance.

Quick Reference

• OBD-II Family: P-Code (Powertrain)
• Scope: Generic
• System: Knock Sensor / Ignition Timing Control
• Difficulty Level: Easy–Moderate
• Estimated Repair Cost: €90–€340+
• Last Updated: 10 December 2025

Real-World Example / Field Notes

A sedan came in with poor throttle response and a persistent P0328 code. The knock sensor wiring was shorted to the 5V reference line due to insulation damage where the harness rubbed against the intake manifold. After repairing the wiring and clearing the code, timing advance returned to normal and performance improved.

Another case involved a vehicle where the sensor had been overtightened during previous engine work, causing it to generate excessive signal output. Installing a new sensor with correct torque immediately resolved the high-input condition.

Symptoms of P0328 – Knock Sensor 1 High Input

• Sluggish acceleration: ECU retards timing to limit potential knock.
• Poor fuel economy: Reduced ignition advance lowers efficiency.
• Pinging or detonation: Possible if timing corrections are inconsistent.
• Rough engine performance: Especially noticeable under load.
• Check engine light: Stored when high voltage input is detected.
• Occasional hesitation: Timing may fluctuate as ECU tries to compensate.

Common Causes of P0328

Most Common Causes

• Short to voltage in knock sensor wiring
• Failed knock sensor producing excessive output
• Connector corrosion or water intrusion
• Improperly torqued knock sensor
• Poor ground connection at the engine block

Less Common Causes

• ECU internal failure
• Aftermarket tuning increasing knock sensitivity
• Severe detonation from low-octane fuel
• Engine mechanical noise interpreted as knock
• Damaged block surface affecting sensor vibration transfer

Diagnosis: Step-By-Step Guide

Diagnosing P0328 requires checking for unintended voltage, wiring faults, sensor sensitivity, and proper mounting conditions.

Tools You’ll Need

OBD-II scanner, multimeter, torque wrench, wiring diagrams, mechanic’s stethoscope, and basic tools.

1. Review freeze-frame data: Check RPM, load, timing advance, and temperature when the fault set.
2. Inspect wiring for shorts: Look for exposed wires touching metal or the 5V reference circuit.
3. Check sensor connector: Look for moisture, corrosion, bent pins, or weak terminal tension.
4. Measure knock sensor voltage: Voltage should remain stable; spikes indicate a fault.
5. Check sensor resistance: Compare with factory specifications for Bank 1 sensor.
6. Verify proper torque: Over-tightening increases signal sensitivity and causes high input.
7. Clean block mounting surface: Ensure proper contact and correct vibration transfer.
8. Inspect for real knock: Severe detonation can cause high-voltage readings.
9. Check for ECU updates: Some vehicles need updated knock-control calibration.
10. Test ground straps: Weak grounding can elevate signal voltage.

Pro Tip: If the knock sensor wiring is shorted to a 5V reference or battery voltage, the ECU will immediately interpret this as a high-input failure — inspect the harness near intake and exhaust components carefully.

Possible Fixes & Repair Costs

• Repair shorted knock sensor wiring: €40–€140
• Replace knock sensor: €70–€150
• Correct torque and clean mounting area: €0–€50
• Replace sensor connector or terminal pins: €40–€120
• Improve engine ground connections: €20–€80
• ECU reflash (if required): €50–€120

Can I Still Drive With P0328?

Yes, but expect reduced performance. The ECU will retard ignition timing to prevent detonation, which may cause sluggish acceleration. However, if real knock is occurring, driving aggressively can risk engine damage. Avoid towing, high RPM, or heavy load until the issue is fixed.

Last updated: March 1, 2026