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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Impala 🢒 Engine 🢒 Engine Controls - 3.4L 🢒 DTC P0327

Circuit Description

The powertrain control module (PCM) contains integrated knock sensor (KS) diagnostic circuitry. The KS produces an AC voltage at all engine speeds and loads. The PCM then adjusts spark timing based on the amplitude and frequency of the KS signal. The PCM uses the KS signal to calculate the average voltage. Then, the PCM assigns a voltage value. The PCM checks the KS and related wiring by comparing the actual knock signal to the assigned voltage range. A normal KS signal should stay outside the assigned voltage range. This DTC will set if the KS signal is within the assigned voltage range or if the KS signal is not present.

Conditions for Running the DTC
    • DTCs P0112, P0113, P0121, P0122, P0123 P0341, P0336, P0506, or P0507 are not set.
    • The engine speed is 1,000-5,000 RPM.
    • The engine has been running for a minimum of 30 seconds.
    • The throttle angle is more than 15 percent .
    • The engine load is more than 40 percent.
    • The engine coolant temperature is more than 60°C (153°F).
    • The maximum spark retard is less than 15 degrees.
    • The system voltage is more than 9 volts.

Conditions for Setting the DTC
    • The PCM detects a knock sensor signal voltage within the calculated average voltage range for at least 10 seconds.
    • The engine run time is more than 30 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Ensures that the malfunction is present.

    2.

  2. If either the 24X crank sensor and the cam signal are not present, the KS signal will stop updating and may set DTC P0327. The 12-volt reference supply and the low reference need to be diagnosed using the DTC P0336.

DTC P0327 - Knock Sensor Circuit

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Using a scan tool, monitor the 24X crank sensor and the cam signal.

Is the 24X signal and cam signal present?

--

Go to Step 3

Go to DTC P0336

3

Important: If a mechanical engine knock can be heard, repair the engine mechanical condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical in Engine Mechanical.

  1. Observe the Freeze Frame and/or Failure Records data for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or as close to the Freeze Frame and Failure Records data that you observed.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4
  1. Turn OFF the ignition.
  2. Disconnect the KS harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the signal circuit of the KS harness connector to a ground.

Does the voltage measure near the specified value?

0 V

Go to Step 6

Go to Step 5

5

Repair the short to voltage in the KS signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 10

--

6
  1. Turn OFF the ignition.
  2. Disconnect the PCM harness connector.
  3. Test the KS circuit for an open or short to ground. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

7
  1. Inspect the KS signal circuit for a poor terminal connection at the Knock Sensor.
  2. If a condition is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step  8

8
  1. Inspect the KS signal circuit for a poor terminal connection at the PCM.
  2. If a condition is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

9

Replace the knock sensor. Refer to Knock Sensor Replacement .

Did you complete the replacement?

--

Go to Step 10

--

10
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 11

Go to Step 2

11

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK