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Code P0327. Symptoms, Causes, Diagnosis and Solution

A Code P0327 is a knock sensor (KS) circuit low voltage trouble code. The knock sensor (KS) provides feedback to the ECM so it can control ignition timing to get the best engine performance without knocking.

The KS sensor is located in the intake manifold. When detonation occurs, the KS produces an alternating current voltage that varies depending on the severity of the detonation.

When the ECM detects knocking, it delays the ignition timing until there is no knocking. The P0327 fault code is a continuous code, meaning the test runs the entire time the engine is running.

KS Knock Sensor Operation

The detection of the engine detonation is the main task of the system knock sensor (KS). This system is especially enabled to allow the ECM module to prevent ignition spark timing based on received signals.

The system is designed in such a way that the KS sensor can generate an AC signal which, under a “no knock” condition in the KS circuit, can read almost 0.007V.

The number of detonations received determines the amplitude and frequency of the KS. A signal-to-noise enhancement filter module (SNEF), is part of the ECM in this circuit.

The SNEF ensures whether any knock is being created based on the comparison of the signals in the KS circuit, including the voltage level in the noise channel.

The noise channel guides the ECM to ignore any inaccurate knock signals by gathering information about the amount of normal engine mechanical noise being created. Engine speed and load are the key factors on which normal engine noise depends.

A DTC will be requested as soon as the ECM understands that an unusually low noise channel voltage level is being regulated.

What is Code P0327?

The P0327 code is called “Knock Sensor (KS) Circuit Low Input (Bank 1, Sensor 1)“. This fault designation applies to all OBD-II-equipped vehicles.

Error code P0327 indicates a low signal level in the knock sensor circuit. That is, the PCM has detected a problem with the knock sensor or its circuit.

Some vehicles may be equipped with more than one knock sensor. This code refers to sensor 1 on bank 1, cylinder 1 side of the engine.

The knock sensor (KS) is installed on the engine and is used to detect abnormal knocking in the engine. When a knock occurs, the sensor emits a voltage signal that is sent to the PCM.

The PCM will then change the ignition advance angle to protect the engine.

Inside the knock sensor is a piezoelectric crystal. This crystal is used to create an alternating voltage during vibration. That is, it is a type of transducer that converts changes in physical quantities into an electrical signal.

The sensor signal wire tells the PCM when a knock occurs and how strong it is. The PCM then reduces ignition timing to prevent premature detonation.

Most PCMs are capable of detecting spark detonation trends in the engine during normal operation.

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Symptoms of Code P0327

The main sign that it has occurred a P0327 error is the malfunction indicator lamp (MIL), also known as the Check Engine.

You may also notice warning signs such as:

  1. The engine runs but with reduced performance (power drop).
  2. Shaking, as well as knocking in the engine.
  3. Higher fuel consumption.
  4. There may be no symptoms other than a stored fault code.

Possible Causes of Code P0327

Among the main causes of the appearance of this code, we can name:

  • Detonation sensor defective or physically damaged.
  • Defective knock sensor wiring.
  • The Knock sensor is poorly tightened in the intake manifold.
  • The knock sensor mounting surface is not free of burrs, dirt, or thread sealant.
  • Incorrect fuel octane rating.
  • Sometimes the cause is a faulty PCM module.

How to Diagnose Code P0327

You must start your diagnosis by connecting the scanner to the car to check the code that is activated.

1. Connect the scanner

  1. Connect the scanner to the car. Check to see if the P0327 code appears initially, along with any other codes. Take note.
  2. Then, clear the code and restart the car for about 10 minutes to check if the fault code appears again.
  3. If it does not appear, you may have an intermittent condition.
  4. If it appears again, proceed with the visual inspection.

2. Visual inspection

  1. Begin the diagnosis by visually inspecting all wiring harnesses and connectors related to the system.
  2. Inspect electrical circuits, sensors, and connectors that are contaminated with engine oil, coolant, or power steering fluid.

3. Sensor test

  1. To test the old knock sensor, connect a multimeter set to AC voltage between the sensor output wire and the ground.
  2. Touch the engine near the sensor. You should see a voltage value on the digital multimeter. If you can’t see any values, the sensor is faulty.
  3. To test the resonant type sensor, connect the digital multimeter in the same way. But instead of hitting the engine block, you’re going to start the car. It is necessary to remove the fuel pump relay to prevent the engine from starting.
  4. Start the engine, run it, and keep your foot on the brake.
  5. As soon as the car starts to run out of fuel, it will start to detonate and stall.
  6. Next, you should see an output voltage on the multimeter. Otherwise, the knock sensor is defective and must be replaced.

4. Check the electrical circuits

  1. If the knock sensor is working properly, but the code P0327 is still activated, you should check the sensor circuit.
  2. With a digital multimeter set to resistance, connect one side of the meter to the wiring harness side of the sensor connector.
  3. And the other to the knock sensor input pin on the PCM. This way we will check the continuity of the circuit between the sensor and the PCM.
  4. Now it is necessary to check the grounding. Older type knock sensors are grounded through the sensor itself, while newer type sensors typically have a separate ground circuit.
  5. Connect the red lead of the multimeter to the positive terminal of the battery and the black lead to the ground.
  6. You should see a value of about 12 volts, which indicates a good ground connection. Otherwise, you should look for some problem in the faulty circuit.

How to Fix Code P0327

Repairs to the system will depend on the results of your diagnosis. Do not proceed to carry out any repairs without first being sure that you have found the fault.

Below is a series of repairs that you can do to the system:

  • Locate the knock sensor connector and disconnect it.
  • Using a digital voltmeter, turn the switch ON without starting the engine, and test each terminal on the connector, connecting one lead from the meter to one terminal and the other lead to a good ground.
  • Each terminal should read 2 to 5 volts. If you don’t see that result, check the wiring harness for an open circuit between the connector and the ECM, a short to ground, or shorted wires.
  • If the voltage is within specifications and the sensor is undamaged and properly torqued, replace the knock sensor.

Is Code P0327 Serious?

The severity of this failure is moderate to high. In some cases, you may be able to drive the car with some difficulty, due to the system’s inability to regulate engine knocking.

In extreme cases, the car may go into fail-safe mode, seeing a loss of power and a speed limit. If this is your case, you should take the car for diagnosis as soon as possible.

We do not recommend that you drive the car if you have activated the code P0327.

How Can I Avoid Code P0327

As you may have noticed, this fault code is specific to the KS knock sensor and its control circuit. Routinely checking the condition of the sensor, as well as the wiring harness, connections, and condition of the cables, can prevent future failure.


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KS knock sensor It plays a vital role in your car’s engine. Controlling engine knocking extends its useful life and improves its efficiency and performance.

If this sensor activates a fault code P0327, you must proceed to diagnosis and repair as soon as possible. If you consider that you cannot do it yourself, we advise you to take the car to a specialized technical service.

Remember that the engine is the heart of your car, and all related systems must work correctly to avoid major failures.

If you want to know other articles similar to Code P0327. Symptoms, Causes, Diagnosis and Solution you can visit the category Fault Codes.


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