GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Spark 🢒 Engine 🢒 Engine Controls - 0.8L 🢒 DTC P0327

Circuit Description

The knock sensor (KS) enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS produces an AC voltage signal that varies depending on the vibration level during engine operation. The ECM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The ECM receives the KS signal through a signal circuit . The ECM supples a ground circuit to the KS through a low reference circuit . The ECM also supplies a shielded ground circuit to the KS. The ECM learns a KS noise level at idle and uses calibrated values for the rest of the engine speed range. The ECM should monitor a normal KS signal within the noise channel. The circuits between the KS sensor and the ECM consists of the following circuits:

    • A signal
    • A low reference
    • A shielded ground

If the ECM detects the KS signal outside of the noise channel, or the KS signal is not present, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0327 Knock Sensor (KS) Circuit Low Frequency.

Conditions for Running the DTC
    • DTCs P0107, and P0108 are not set.
    • The engine coolant temperature (ECT) is more than 80°C (176°F).
    • The engine speed is more than 2,500 RPM.
    • DTC P0327 runs continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects an incorrect KS signal for more than 4 seconds.

Action Taken When the DTC Sets
    • The malfunction indicator lamp (MIL) will illuminate.
    • The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.
    • A history DTC is stored.

Conditions for Clearing the MIL/DTC
    • The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • DTCs can be cleared by using the scan tool.

Diagnostic Aids
    • Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set.
    • Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS should be free of thread sealant. The KS mounting surface should be free of burrs, casting flash, and foreign material.
    • The KS must be clear of hoses, brackets, and engine electrical wiring.
    • For an intermittent condition, refer to Intermittent Conditions .

Test Description

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

  1. This step tests for a short to voltage in the signal circuit of the KS.

    2.

  2. This step tests for a short to ground in the signal circuit of the KS.

    3.

  3. This step tests for an open or high resistance in the signal circuit or low reference circuit of the KS.

    4.

  4. This step tests for an open or high resistance in the low reference of the KS.

    5.

  5. This step tests for an open or high resistance in the shielded ground circuit of the KS.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Important: If an engine mechanical noise can be heard, repair the condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical in Engine Mechanical - 0.8L (LBF).

  1. Start the engine.
  2. Operate the engine within the Conditions for Running the DTC.
  3. Observe the DTC information with a scan tool.

Did DTC P0327 fail this ignition?

--

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn the ignition OFF for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4
  1. Turn OFF the ignition.
  2. Disconnect the knock sensor (KS) harness connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp from the signal circuit of the KS to a good ground.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 5

5

Connect a test lamp from the signal circuit of the KS to a battery voltage.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 6

6
  1. Turn OFF the ignition.
  2. Measure the resistance from the signal circuit to the low reference circuit of the KS on the controller side of the KS harness connector with the DMM.

Is the resistance within the specified range?

90K-110K ohms

Go to Step 8

Go to Step 7

7

Measure the resistance from the low reference circuit of the KS on the controller side of the KS harness connector to a good ground with the DMM.

Is the resistance less than the specified value?

5 ohms

Go to Step 9

Go to Step 10

8

Measure the resistance from the shielded ground circuit on the controller side of the KS harness connector to a good ground with the DMM.

Is the resistance less than the specified value?

5 ohms

Go to Step 12

Go to Step 11

9

Test the signal circuit of the KS for one of the following conditions:

    • An open
    • A short to ground
    • A short to voltage
    • High resistance
    • A short between both circuits

Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

10

Test the low reference circuit of the KS for one of the following conditions:

    • An open
    • High resistance

Refer to Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

11

Test the shielded ground circuit of the KS for the following conditions:

    • An open
    • A high resistance

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

12

Test for an intermittent and for a poor connection at the KS. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

13

Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 15

14

Replace the KS. Refer to Knock Sensor Replacement .

Did you complete the replacement?

--

Go to Step 16

--

15

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

16
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 17

17

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK