Error Code P0328 is defined as Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor). Meaning, this code refers to a fault in the knock sensor 1 circuit.

This is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II, particularly vehicles made since 1996 up to present. Specifications on the definition, troubleshooting and repairs of course, vary from one make and model to another.

Definition

Knock sensors (KS) are included in the engine to detect engine pre-detonation, such as pining and knocking. It’s a two wire sensor supplied with 5V reference voltage, with a signal return linked to the PCM.

Thus, the error code P0326 means the PCM (powertrain control module, also known as ECM or engine control module) has detected a reference voltage coming from the knock sensor which has fallen outside the accepted threshold set by the vehicle’s manufacturer. The job of the knock sensor is to send a signal to the PCM indicating abnormal noises in the engine that may be occurring, like spark knock. It also tells the PCM the severity of the knocks. With this, the PCM will retard the spark timing to avoid pre-detonation.

Error Code P0328 means there’s a high input coming from the bank 1 sensor 1. This happens when the PCM detects excessively high voltage way out of the specified range from the knock sensor.

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Common Symptoms

Some of the most common symptoms include:

  • Some slight engine hesitation
  • Engine loss of power
  • In some cases, the vehicle may exhibit pinging noise at higher RPMs
  • Engine running warmly

Possible Causes

There are multiple reasons a vehicle can have this problem, which include:

  • Damaged knock sensor connector
  • Open or shorted to ground knock sensor circuit
  • Shorted to voltage knock sensor circuit
  • Loose knock sensor
  • Damaged knock sensor
  • Low fuel pressure
  • Wrong fuel octane
  • Circuit experiencing electrical interference
  • Mechanical engine problem
  • Overheating engine
  • Failed PCM (rare)

How to Check

As with other error codes, diagnosis for Error Code P0328 starts with the use of scan tool hooked into the DLC port to check the verify the present code(s) and gather the freeze frame data associated with the code.

The codes are then cleared and the vehicle will be taken for a test drive, duplicating the conditions that set the code. The technician will take note of any knocking sound on the engine.

Then, he will conduct a visual inspection of the engine, and look for faults. He will check the cooling system as well as the engine. He will also check the fuel octane and the fuel system for knocking.

The scan tool is then used to monitor any changes in the knock sensor voltage if the engine is not knocking. The scan tool will also be used to check the engine coolant temperature for the fuel pressure.

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The PCM will then be tested; each vehicle has its own PCM testing procedure.

How to Fix

If there is an engine knocking (detonation), first thing technicians do is to fix the mechanical problem and retest the vehicle. They make sure the vehicle is using the correct octane fuel. Some engines may require premium fuel, so it pays to check the owner’s manual. Also, the most common source of this problem is in the knock sensor itself, connectors or wirings of the sensors to the PCM. Thus, these things should be checked first and repair or replace as necessary. Other common fixes include:

  • Repairing or replacing the knock sensor wiring harness
  • Replacing faulty ECU
  • Replacing bank 1 knock sensor 1
  • Repair fuel problems
  • Repair overheating engine

It can be tricky to diagnose Error Code P0328 if the right steps are not followed, and many different aspects and systems of the vehicle can be overlooked and can lead to this code. Thus, a professional level scan tool is very important for a thorough diagnosis of this code.

Though symptoms are rather mild and doesn’t always cause serious drivability issues, it leads the engine to run hot, which is why it is crucial to fix this problem.