GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1998 🢒 Trans Sport Ext. 🢒 DTC 🢒 DTC P0325 Knock Sensor (KS) Circuit

Object Number: 259359 Size: LF
Engine Controls Components
Ignition System, Knock Sensor
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 sensor produces an AC signal under all engine operating conditions. If the PCM malfunctions in a manner which will not allow proper diagnosis of the KS circuits, DTC P0325 will set.

Conditions for Running the DTC
  1. No TP sensor, VSS, CMP, CKP, MAF, or ECT DTCs are set.
  2. Engine speed is between 1000 and 5000 rpm.
  3. Throttle angle is greater than 10%.
  4. Engine load is greater than 55%.
  5. Engine coolant temperature is greater than 75°C (167°F).
  6. Maximum spark retard is less than 15 degrees.
  7. 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.

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.
    •  The PCM will use a calculated spark retard value to minimize knock during conditions when knock is likely to occur. The calculated value will vary based on engine speed and load.

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.

Test Description

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

  1. Ensures that the malfunction is present.

    2.

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

    3.

  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 (General Description) 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

Refer to Diagnostic Aids

4

Important: :  The replacement PCM must be programmed. Go 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