P0325

DTC P0325: Knock Sensor (KS) Circuit

Wiring Diagram:

System Description
The Knock Sensor (KS) system is used to detect engine detonation, allowing the Engine Control Module (ECM) to retard the ignition control spark timing based on the KS signal being received. The KS produces an AC signal so that under a no-knock condition the signal on the KS circuit measures about 0.007 V AC. The KS signal's amplitude and frequency depend upon the amount of knock being experienced. The ECM monitors the KS signal and can diagnose the KS and circuitry.

Conditions for Setting the DTC
- Vacuum is less than the predetermined value (10 - 50 kPa, based on RPM).
- The RPM is less than 1,600 rpm.
- Filter coefficient is less than 1.0%.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- The DTC(s) can be cleared by using the scan tool.
- Disconnecting the ECM battery feed for more than 10 seconds.
- The MIL will turn OFF after four consecutive ignition cycles in which the diagnostic runs without a fault.

Diagnostic Aids
Check and correct any abnormal engine noise before using the diagnostic table.
Any circuitry, that is suspected as causing the complaint, should be thoroughly checked for the following conditions:
- Backed-out terminals
- Improper mating
- Broken locks
- Improperly formed
- Damaged terminals
- Poor terminal-to-wire connection
- Physical damage to the wiring harness

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred.
The information is then stored on the scan tool for later reference.
2. If the conditions for the test as described above are met, a DTC P0325 will set and MIL will illuminate.
3. If the engine has an internal knock or audible noise that causes a knocking type noise on the engine block, the KS may be responding to the noise.
4. Checking the internal resistance of the KS or the wiring to the KS is OK.
5. Any circuitry, that is suspected as causing the complaint, should be thoroughly checked for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wiring connections or physical damage to the wiring harness.
6. The replacement ECM must be reprogrammed.
Refer to the latest Techline procedure for ECM reprogramming.

Step 1-6:

Step 7-12:

Troubleshooting