P0325

DTC P0325: Knock Sensor Circuit

CAUTION:
If DTC P0325 has been set, TCL related DTC U1120 is also set. After P0325 has been diagnosed, don't forget to erase DTC U1120.














CIRCUIT OPERATION

- The knock sensor sends a signal voltage to the ECM[ M/T] or the PCM[ A/T] (terminal No. 59).

TECHNICAL DESCRIPTION

- The knock sensor converts the vibration of the cylinder block into a voltage and outputs it. If there is a malfunction of the knock sensor, the voltage output will not change.
- The ECM[ M/T] or the PCM[ A/T] checks whether the voltage output changes.

DESCRIPTIONS OF MONITOR METHODS

- Knock sensor signal does not change.

MONITOR EXECUTION

- Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

- Not applicable
Sensor (The sensor below is determined to be normal)

- Not applicable

DTC SET CONDITIONS

Logic Flow Chart





Check Conditions

- 2 seconds or more have passed since the starting sequence was completed.
- Engine speed is higher than 2,500 r/min.
- Volumetric efficiency is 40% or more.
Judgement Criterion

- Knock sensor output voltage (knock sensor peak voltage in each 1/2 turn of the crankshaft) has not changed for 2 seconds.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 7 Monitors, Trips, Drive Cycles and Readiness Codes .

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

- Knock sensor failed.
- Open or shorted knock sensor circuit, harness damage or connector damage.
- ECM failed.[ M/T]
- PCM failed.[ A/T]

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Check harness connector B-126 at the knock sensor for damage.





Q. Is the harness connector in good condition?

YES Go to Step 2.

NO Repair or replace it. Harness Connector Inspection.
Then go to Step 6.

STEP 2. Check the continuity at knock sensor harness side connector B-126.





(1)Disconnect the connector B-126 and measure at the harness side.





(2)Check for the continuity between terminal No. 2 and ground.

- Continuity (2ohms or less)

Q. Does continuity exist?

YES Go to Step 3.

NO Repair harness wire between knock sensor connector B-126 (terminal No. 2) and ground because of open circuit or harness damage. Then go to Step 6.

STEP 3. Check harness connector B-20 at ECM [M/T]
or PCM [A/T]
for damage.





Q. Is the harness connector in good condition?

YES Go to Step 4.

NO Repair or replace it. Harness Connector Inspection.
Then go to Step 6.

STEP 4. Check for open circuit and short circuit to ground and harness damage between knock sensor connector B-126 (terminal No. 1) and ECM [M/T]
or PCM [A/T]
connector B-20 (terminal No. 59).









Q. Is the harness wire in good condition?

YES Go to Step 5.

NO Repair it. Then go to Step 6.

STEP 5. Check the knock sensor.





(1)Disconnect the knock sensor connector B-126.
(2)Start the engine and run at idle.





(3)Measure the voltage between knock sensor side connector terminal No. 1 (output) and No.
2 (ground).
(4)Gradually increase the engine speed.

- The voltage increases with the increase in the engine speed.
(5)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the sensor operating properly?

YES Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Encrypted Code Registration Criteria Table.
Then go to Step 6.

NO Replace the knock sensor. Then go to Step 6.

STEP 6. Test the OBD-II drive cycle.

(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 7 Monitors, Trips, Drive Cycles and Readiness Codes.

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P0325 set?

YES Retry the troubleshooting.
NO The inspection is complete.