For 1990-2009 cars

### Circuit Description

The knock sensor (KS) produces an alternating current voltage at all engine speeds and loads. The powertrain control module (PCM) adjusts spark timing based on the amplitude and on the frequency of the KS signal. The PCM uses the KS signal in order to calculate the average voltage and assigns a voltage value. The PCM checks the KS and the 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 diagnostic trouble code (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 P0101, P0102, P0103, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0336, P0341, P0502, P0503, P1114, P1115, P1121, P1122, P1336 are not set.

• | The engine speed is between 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 45 percent .

• | The engine coolant temperature (ECT) is more than 60°C (140°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 KS signal voltage within the 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.

### Diagnostic Aids

Important: If the KS is dropped, the sensor must be replaced.

• | Check the KS for proper installation. A KS that is loose or over torqued may cause the DTC to set.

• | For an intermittent, refer to Intermittent Conditions .

### Test Description

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

1. This step ensures that the malfunction is present.

2. Tapping on the engine block will simulate an engine knock.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Component Views or Powertrain Control Module 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 |

1. Install a scan tool.
2. Start the engine.
3. Monitor the Diagnostic Trouble Code (DTC) information using the scan tool.

Does the scan tool display any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3 | Important: If a mechanical engine knock can be heard, repair the engine mechanical condition before continuing with this diagnostic test.

1. Observe the Freeze Frame/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 in the DTC or as close to the Freeze Frame/Failure Records data that you observed.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4 |

1. Disconnect the KS harness.
2. Set the DMM to the 400K-ohm scale.
3. Measure the resistance of the KS using the DMM connected to a good ground.

Is the resistance of the KS near the specified range?

100K ohms

Go to Step 5

Go to Step 9

5 |

1. With the DMM still connected, set the DMM to the 400-mV alternating current Hertz scale. Refer to Measuring Frequency in Wiring Systems.

Important: Do not tap on plastic engine components.

2. Tap on the engine block near the KS while observing the signal indicated on the DMM.

Is any signal indicated on the DMM while tapping on the engine block near the KS?

--

Go to Step 6

Go to Step 9

6 |

1. Turn OFF the ignition.
2. Disconnect the PCM harness connector.
3. Test the KS circuit for the following conditions and refer to Circuit Testing in Wiring Systems:

• | An open or a high resistance

• | A short to ground

• | A short to voltage

Did you find and correct the condition?

--

Go to Step 11

Go to Step 7

7 |

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

Did you find and correct the condition?

--

Go to Step 11

Go to Step 8

8 |

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

Did you find and correct the condition?

--

Go to Step 11

Go to Step 10

9 | Replace the KS. Refer to Knock Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
10 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
11 |

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.

Does the DTC run and pass?

--

Go to Step 12

Go to Step 2

12 | 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