For 1990-2009 cars
Engine Controls Components
Ignition Controls
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 knock sensor produces an AC signal. 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 5 seconds.

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

• | System voltage is greater than 9 volts.

• | Engine speed between 550 and 850 rpm.

### 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 Failure 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.

• | The DTC can be cleared by using the scan tool Clear Info function.

### Diagnostic Aids

Check for the following conditions:

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

• | Damaged or improperly installed KS. Check for bent pins, deformed terminals.

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.

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. Refer to Powertrain Control Module Replacement/Programming .

#### 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 | Important: : The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. 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