P0325
DTC P0325 KNOCK SENSOR 1 CIRCUIT MALFUNCTION (BANK 1)Component Location:
GENERAL DESCRIPTION
Knocking is a phenomenon characterized by undesirable vibration and noise and can cause engine damage. The knock sensor (KS) is attached to the cylinder block and senses engine knocking. A knocking vibration from the cylinder block is applied as pressure to the piezoelectric element. The knock sensor (KS) detects vibration upon increase and decrease in engine RPM and generates a voltage based on this vibration. The PCM controls the ignition timing based on the amplitude and frequency of the knock sensor signal. For example, if engine knocking occurs, the ignition timing is recarded to suppress it. This DTC is set when the frequency goes outside a calibrated level.
DTC DESCRIPTION
The PCM monitors the range of the analog input signal from knock sensor to check sensor failure that is short circuit or open circuit. If the difference between knock signal and noise level is smaller than the threshold during d.fined time period, the DTC P0325 is set. In case the noise level is higher than the upper threshold or lower than the lower threshold, the DTC P0325 is set too. If same error code is set in the next driving cycle, the PCM illuminates the MIL.
DTC Detecting Condition:
Specification:
Schematic Diagram:
SIGNAL WAVEFORM & DATA
This figures show the wave form measured at terminal 1 of knock sensor at idle.
1. Check if the output voltage of knock sensor at idle is 0.4 V.
2. In case the output voltage is over 3.5 V.
The knock sensor is fitted to the cylinder block to successfully sense vibration when the engine operates. The waveform shown is the knock sensor signal characteristic and indicates that no knocking has place. The knocking signal generally appears as a noise that is higher than other signals.
MONITOR DTC STATUS
This is the inspection procedure to determine whether it is present DTC or memoried one by monitoring the current signal or by using the function of oscilloscope with Hi-scan pro.
1. Connect scantool to Data Link Connector(DLC).
2. Warm up the engine to normal operating temperature.
3. Monitor the "ignition timing" parameter on the scantool.
NOTE: The data shown above is only for reference and there maybe a little difference actually.
Specification
Idle: 0 - 20° BTDC
3000 rpm : 29 - 49° BTDC
4. Is parameter displayed within specifications?
YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared.
Thoroughly check connectors for looseness, poor connection, bending, corrosion,contamination,deterioration, or dama9e. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO: Go to "W/Harness Inspection" procedure.
TERMINAL & CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination,deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of vehicle Repair" procedure.
NO: Go to "Signal circuit inspection" procedure.
SIGNAL CIRCUIT INSPECTION
1. Check for open in harness
1. Ignition "OFF"
2. Disconnect Knock sensor connector.
3. Ignition "ON" & Engine "OFF"
4. Measure voltage between terminal 2 of sensor harness connector and chassis ground.
Specification: approximately 0.4 V
5. Is measure voltage within Specification?
YES: Go to "Check for short to ground in harness as below.
NO:
- In case over 5 V: Short circuit to battery between Knock sensor harness connector and PCM harness connector.
- In case 0 V: Open or Short circuit between Knock sensor harness connector and PCM harness connector
- Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
NOTE: In case,when knock sensor connector is disconnected, the voltage at terminal 1 is 0 V.
- Possible cause : Open or short to ground and faulty PCM.
2. Check for short to ground in harness
1. Ignition "OFF"
2. Disconnect Knock sensor connector and PCM connector.
3. Ignition "ON" & Engine "OFF"
4. Measure resistance between terminal 2 of sensor harness connector and chassis ground.
5. Measure resistance between terminal 1 and 2 of sensor harness connector.
Specification: infinite
6. Is measure resistance within Specification?
YES: Go to "Ground Circuit Inspection" procedure.
NO:
- Short circuit to chassis ground between Knock sensor harness connector and PCM harness connector.
- Short circuit between Knock sensor signal line and ground line.
- Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
GROUND CIRCUIT INSPECTION
1. Ignition "OFF"
2. Disconnect Knock sensor connector.
3. Ignition "ON" & Engine "OFF"
4. Measure resistance or voltage between terminal 1 of sensor harness connector and chassis ground.
Specification: below 1 Ohms, below 0.5 V
5. Is measure voltage or resistance within Specification?
YES: Go to "Component Inspection" procedure.
NO:
- Open circuit between Knock sensor harness connector and PCM harness connector.
- Open circuit between PCM harness connector and chassis ground.
- Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
NOTE: In case, when checking the open ground circuit, the resistance is infinite.
- Possible cause: Open circuit in ground line.
COMPONENT INSPECTION
1. Check Knock sensor
1. Measure resistance between terminal 1 and 2 of sensor connector(To sensor side)
Specification 20 °C(68 °F) about 5 MOhms ± 0%
2. Does each resistance indicate continuity circuit?
YES: Substitute with a known-good PCM and check for proper operation. If the problem is corrected, replace PCM and then go to "Verification of Vehicle Repair" procedure.
NO: Substitute with a known-good Knock sensor and check for proper operation. If the problem is corrected, replace Knock sensor and then go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code (DTC) which has been diagnosed.
2. using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all rediness test have been verified as "Complete"
5. Are any DTCs present?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time.