For 1990-2009 cars
Engine Controls Components
Ignition System, Knock Sensor
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The knock sensors are used to detect engine detonation, allowing the PCM to retard Ignition Control (IC) spark timing based on the KS signal being received. The signal amplitude and frequency is dependent upon the amount of knock being experienced.

The PCM determines whether knock is occurring by comparing the signal level on the KS circuit with the voltage level on the noise channel. The noise channel allows the PCM to reject any false knock signal by indicating the amount of normal engine mechanical noise present. Normal engine noise varies depending on engine speed and load.

### Conditions for Setting the DTC

• | No active VSS, TP sensor, ECT sensor DTC(s) set.

• | Engine has been running for at least 10 seconds.

• | Engine coolant temperature is greater than 65°C (149°F).

• | Throttle angle is greater than 10%.

• | Engine speed is between 2200 RPM and 2500 RPM.

• | System voltage is greater than 9 volts.

• | The PCM is monitoring a ESC noise channel voltage level below 0.4 volt.

### Action Taken When the DTC Sets

• | The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

• | The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

### Conditions for Clearing the MIL/DTC

• | A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

### Diagnostic Aids

Check for the following conditions:

• | Poor connection at PCM. Inspect knock sensor and PCM connectors for backed out terminals, broken locks, and improperly formed or damaged terminals.

• | Misrouted harness. Inspect the knock sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table:

1. Ensures that the malfunction is present.

2. If sent here from symptoms, proceed with the diagnostic table.

#### DTC P0327 - Knock Sensor Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to the Powertrain On Board Diagnostic (OBD) System Check
2 | Important: : If a mechanical engine knock can be heard, repair the engine mechanical problem before proceeding with this diagnostic. Refer to Engine Noise Diagnosis (General Description) in Engine Mechanical.

1. Operate the engine within conditions specified in Conditions for Setting the DTC.
2. Using a scan tool, monitor Specific DTC info for DTC P0327 until the DTC P0327 test runs.

Does scan tool indicate DTC P0327 failed this ignition?

--

Go to Step 4

Go to Step 3

3 |

1. Turn ON the ignition switch, engine not running.
2. Review and record scan tool Fail Records data for DTC P0327.
3. Operate vehicle within Fail Records conditions.
4. Using a scan tool, monitor Specific DTC info for DTC P0327 until the DTC P0327 test runs.

Does the scan tool indicate DTC P0327 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 |

1. Disconnect the PCM and the Knock Sensor.
2. Check the KS circuit for opens and shorts to ground.
3. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was problem found?

--

Go to step 7

Go to Step 5

5 |

1. Check the KS signal circuit for a poor terminal connection at the knock sensor.
2. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems.

Was problem found?

--

Go to Step 7

Go to Step 6

6 | Replace the knock sensor. Refer to Knock Sensor Replacement . Is the action complete? | -- | Go to Step 7 | --
7 |

1. Review and record Fail Records data.
2. Clear DTCs.
3. Operate the vehicle within Fail Records conditions.
4. Using a scan tool, monitor Specific DTC info for DTC P0327 until the DTC P0327 test runs.

Does the scan tool indicate DTC P0327 failed this ignition?

--

Go to Step 2

System OK