For 1990-2009 cars
Engine Controls Components
Ignition Controls
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

### Circuit Description

The knock sensor (KS) system detects for an engine detonation. The knock sensor produces an AC voltage signal. The amplitude and the frequency of the AC voltage signal is dependent upon the knock level being detected. This signal then travels to the KS module that is an internal part of the Powertrain Control Module (PCM). If knock is detected, the PCM will retard the spark timing based on the signal from the knock sensor.

### Conditions for Setting the DTC

• | Engine run time is greater than 20 seconds.

• | Engine Coolant Temperature (ECT) is greater than 56°C (131°F).

• | Engine speed is above 1600 RPM.

• | MAP is greater than 60 kPa.

• | Engine vacuum is less than 33 kPa.

• | The KS voltage and variation is not within normally expected ranges.

• | The above conditions are present for greater than 60 seconds.

### Action Taken When the DTC Sets

• | The Malfunction Indicator Lamp (MIL) will illuminate.

• | The PCM will record operating conditions at the time the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.

• | A history DTC stores.

• | The coolant fan turns ON.

• | The PCM will default to 6 degrees timing.

### Conditions for Clearing the MIL/DTC

• | The MIL will turn OFF after three 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.

• | The MIL/DTCs can be cleared by using the scan tool.

### Diagnostic Aids

• | Check and correct any abnormal engine noise before using the diagnostic table.

• | Thoroughly check any suspected circuitry for the following conditions:

- | Backed out terminals

- | Improper mating

- | Broken locks

- | Improperly formed connectors

- | Damaged terminals

- | Poor terminal to wiring connections

- | Physical damage to the wiring harness

### Test Description

The numbers below refer to the step numbers on the Diagnostic Table.

1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the this DTC set. The scan tool stores this data for later reference.

2. If the conditions for the test as described above are met, a DTC P0325 will set and the MIL will illuminate.

3. If the engine has an internal knock or an audible noise that causes a knocking type of noise on the engine block, this is an indication that the knock sensor may be responding to the noise.

4. This step checks the internal resistance of the knock sensor or the wiring to the knock sensor.

5. Thoroughly check any suspected circuitry for the following conditions:

• | Backed out terminals

• | Improper mating

• | Broken locks

• | Improperly formed or damaged terminals

• | Poor terminal to wiring connections

• | Physical damage to the wiring harness

6. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Techline information for PCM programming and the Crankshaft Position System Variation Learn .

#### DTC P0325-Knock Sensor (KS) Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn ON the ignition switch leaving the engine OFF.
2. Install a scan tool.
3. Review the Freeze Frame data and record the parameters.
4. Start the engine.
5. Operate the vehicle within the Conditions For Setting the DTC as specified in the supporting text.

Does the Malfunction Indicator Lamp (MIL) illuminate?

--

Go to Step 3

Go to Step 11

3 | Listen to the engine while raising and lowering the engine speed. Is a knock or audible noise present? | -- | Go to Step 4 | Go to Step 5
4 |

1. Turn OFF the ignition switch.
2. Check and repair the following conditions:

• | Mechanical engine problem

• | Loose bracket

• | Component

Is the action complete?

--

Go to Step 11

--

5 |

1. Turn OFF the ignition switch.
2. Disconnect the PCM electrical connectors at the PCM.
3. Connect a DMM to ground.
4. Measure the resistance of the knock sensor through the knock sensor signal circuit (sensor side).

Is the measured value within the specified value?

90K-110Kohms

Go to Step 6

Go to Step 8

6 |

1. Check the knock sensor signal circuit for a poor electrical terminal connection at the PCM.
2. Repair the circuit as necessary. Refer to the Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 11

Go to Step 7

7 | Replace the PCM. Refer to the Powertrain Control Module Replacement . Is the action complete? | -- | Go to Step 11 | --
8 |

1. Check the knock sensor electrical connector for a poor electrical connection.
2. Repair the electrical connector as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 11

Go to Step 9

9 |

1. Check the knock sensor signal circuit for the following conditions:

• | Open circuit

• | Short to ground

• | Short to voltage

2. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

--

Go to Step 11

Go to Step 10

10 | Replace the Knock Sensor (KS). Refer to the Knock Sensor Replacement . Is the action complete? | -- | Go to Step 11 | --
11 |

1. Clear the DTCs with the scan tool.
2. Start the engine.
3. Idle the engine at the normal operating temperature.
4. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has ran and passed?

--

Go to Step 12

Go to Step 3

12 | Check to see if any DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to applicable DTC table | System OK