For 1990-2009 cars
Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The PCM contains integrated Knock Sensor (KS) diagnostic circuitry. An input signal from the knock sensor is used to detect engine detonation, allowing the PCM to retard Ignition Control (IC) spark timing based on the amplitude and frequency of the KS signal being received. The knock sensors produce an AC signal under all engine operating conditions. During engine operation, the PCM calculates the average voltage of the knock sensor signal. If the PCM malfunctions in a manner which will not allow proper diagnosis of the KS circuit, DTC P0325 will set.

### Conditions for Running the DTC

• | No TP sensor, VSS, CKP sensor, CMP sensor, MAF, or ECT DTCs are set.

• | Engine speed is between 1000 and 5000 RPM.

• | The engine has been running for a minimum of 30 seconds.

• | Throttle angle is greater than 15%.

• | Engine load is greater than 45%.

• | Engine coolant temperature is greater than 60°C (140°F).

• | Maximum spark retard is less than 15 degrees.

• | System voltage is greater than 9 volts.

### Conditions for Setting the DTC

• | The PCM detects a malfunction in the integrated knock sensor diagnostic circuitry which will not allow proper diagnosis of the knock sensor circuits.

• | Above conditions for at least 30 seconds.

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

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

• | The DTC can be cleared by using a scan tool.

### 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.

3. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

#### DTC P0325 - Knock Sensor Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain 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 in Engine Mechanical.

1. Operate engine within conditions specified in diagnostic support. Refer to Conditions for Setting the DTC.
2. Using a scan tool, monitor Specific DTC info for DTC P0325 until the DTC P0325 test runs.

Note test result, does scan tool indicate DTC P0325 failed this ignition?

--

Go to Step 4

Go to Step 3

3 |

1. Turn on the ignition switch.
2. Review and record scan tool Fail Records data for DTC P0325.
3. Operate vehicle within Fail Records conditions.
4. Using a scan tool, monitor Specific DTC info for DTC P0325 until the DTC P0325 test runs.

Does scan tool indicate DTC P0325 test failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4 | Replace the PCM. Important: : The replacement PCM must be programmed. Go to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 5 | --
5 |

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 P0325 until the DTC P0325 test runs.

Does the scan tool indicate DTC P0325 test failed this ignition?

--

Go to Step 2

System OK