DTC P0021: "A" Camshaft Position - Timing Over-Advanced Or System Performance Bank 2: Notes

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:

Engine stalls.
Improper idling

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode Ref. to ENGINE (DIAGNOSTICS) (H4DO)>CLEAR MEMORY MODE>OPERATION ., and inspection mode Ref. to ENGINE (DIAGNOSTICS) (H4DO)>INSPECTION MODE>PROCEDURE .
Use the check board when measuring the ECM terminal voltage and resistance.

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

Courtesy of SUBARU OF AMERICA, INC.

Courtesy of SUBARU OF AMERICA, INC.

CHECK DTC .
Read the engine DTC using the Subaru Select Monitor or general scan tool. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>READ DIAGNOSTIC TROUBLE CODE (DTC) .

Are DTCs other than P000C and P0021 displayed? (Current malfunction)

Yes: Check the appropriate DTC using "List of Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .

No: Save the freeze frame data. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>SUBARU SELECT MONITOR>OPERATION>DISPLAY OF ENGINE FREEZE FRAME DATA , Go to 2 .
CHECK ENGINE OIL CONDITION .
Check the engine oil condition.
NOTE:
Check the following items.
- Oil amount is within the specified range
- Occurrence of abnormal dirt
- Coagulation due to additives
- Use of oil with specified viscosity
Is the check result OK?

Yes: Go to 3 .

No: Adjust oil amount or replace the engine oil and oil filter. Ref. to LUBRICATION (H4DO)>ENGINE OIL . Ref. to LUBRICATION (H4DO)>ENGINE OIL FILTER . Go to 3 .
CHECK ON-BOARD MONITOR TEST RESULTS .
1. Replace the intake oil control solenoid LH. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>OIL CONTROL SOLENOID .
2. Perform the Clear Memory Mode for the engine using the Subaru Select Monitor or a general scan tool. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>CLEAR MEMORY MODE .
3. Perform drive cycle T. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>DRIVE CYCLE .
4. Read values of "VVT Monitor Bank 1" and "VVT Monitor Bank 2" according to MODE $06 reading procedures using the Subaru Select Monitor or general scan tool. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>GENERAL SCAN TOOL>OPERATION>MODE $06 (REQUEST ON-BOARD MONITORING TEST RESULTS FOR CONTINUOUSLY MONITORED SYSTEMS) .
  CAUTION:
  - When performing driving cycle, there should be 2 persons (driver and checker) and the checker should perform the data check.
  - When performing the drive cycle on the public road, be very careful of the traffic condition and the safe driving must be the high priority.
  NOTE:
  - When the diagnostic value is 0, the diagnosis is incomplete. therefore, do not stop the engine and perform the drive cycle again.
  - Diagnostic values are updated repeatedly, and therefore, always check the data while diagnostic values are being read.
5. Record the read values in "VVT Monitor Bank 1" and "VVT Monitor Bank 2".
Is the value in "VVT Monitor Bank 2" of the replaced oil control solenoid 1000 or more?

Yes: Go to 5 .

No: Go to 4 .
CHECK ON-BOARD MONITOR TEST RESULTS .
Compare the values in "VVT Monitor Bank 1" and "VVT Monitor Bank 2" recorded in step 3.

Is the value in "VVT Monitor Bank 2" 1000 or less, and also larger than the value (value in "VVT Monitor Bank 1" x 1.5+100) compared to the value in "VVT Monitor Bank 1"?

Yes: Go to 5 .

No: Idle the engine for five minutes, and then replace (flush) the oil filter and engine oil. Ref. to LUBRICATION (H4DO)>ENGINE OIL Ref. to LUBRICATION (H4DO)>ENGINE OIL FILTER . Go to 14 .
CHECK HARNESS AND CONNECTOR .
Check the harness and connector for bending, damage and poor contact.
NOTE:
Check the following items.
- ECM Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>ENGINE CONTROL MODULE (ECM) .
- Oil control solenoid Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>OIL CONTROL SOLENOID .
- Camshaft position sensor Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CAMSHAFT POSITION SENSOR .
- Crankshaft position sensor Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CRANKSHAFT POSITION SENSOR .
Is the check result OK?

Yes: Go to 6 .

No: Repair or replace faulty parts. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>ENGINE CONTROL MODULE (ECM) . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>OIL CONTROL SOLENOID . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CAMSHAFT POSITION SENSOR . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CRANKSHAFT POSITION SENSOR . Go to 6.
CHECK HARNESS AND CONNECTOR (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connector from the intake oil control solenoid LH.
4. Measure the resistance of harness between ECM connector and intake oil control solenoid LH connector.
  Connector & terminal
  
  (E158) No. 6 - (E37) No. 2:
Is the resistance 1 Ω or less?

Yes: Go to 7 .

No: Repair or replace faulty parts. Go to 14 .
CHECK HARNESS AND CONNECTOR (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connector from intake camshaft position sensor LH.
4. Measure the resistance between intake camshaft position sensor LH connector and ECM connector.
  Connector & terminal
  
  (E158) No. 41 - (E35) No. 2:
Is the resistance 1 Ω or less?

Yes: Go to 8 .

No: Repair or replace faulty parts. Go to 14 .
CHECK HARNESS AND CONNECTOR (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connector from the crankshaft position sensor.
4. Measure the resistance between crankshaft position sensor connector and ECM connector.
  Connector & terminal
  
  (E158) No. 40 - (E10) No. 1:
Is the resistance 1 Ω or less?

Yes: Go to 9 .

No: Repair or replace faulty parts. Go to 14 .
CHECK ENGINE OIL PRESSURE .
Check the engine oil pressure. Ref. to MECHANICAL (H4DO)>ENGINE OIL PRESSURE .

Is the engine oil pressure normal?

Yes: Go to 11 .

No: Go to 10 .
CHECK OIL STRAINER .
Check the oil strainer. Ref. to LUBRICATION (H4DO)>OIL PAN .

Are there any foreign matter mixed in oil strainer in the oil pan?

Yes: Check and clean inside the oil strainer. Go to 11 .

No: Replace the chain cover. Ref. to MECHANICAL (H4DO)>CHAIN COVER .

CAUTION: Excessive application of liquid gasket during assembly of the chain cover may cause malfunction. Use the type specified in the service information and apply appropriate amount (wire diameter). Ref. to MECHANICAL (H4DO)>CHAIN COVER>INSTALLATION .

Go to 12 .
CHECK OIL PASSAGES OF CHAIN COVER .
1. Remove the engine from the vehicle. Ref. to MECHANICAL (H4DO)>ENGINE ASSEMBLY .
2. Check oil passages of chain cover. Ref. to MECHANICAL (H4DO)>CHAIN COVER .
  NOTE:
  Check that the following oil passages have O-rings and that there is no foreign matter.
  - Inlet port of oil pump
  - Discharge port of oil pump
  - Each O ring at passages to left and right cylinder heads
  - Oil control solenoid
  - Entry of foreign matter
Is the check result OK?

Yes: Go to 12 .

No: Replace the defective parts. Replace the chain cover in the case of foreign matter entry. Ref. to MECHANICAL (H4DO)>CHAIN COVER .

Go to 12 .
CHECK THE CONDITION OF CAMSHAFT .
1. Remove the timing chain. Ref. to MECHANICAL (H4DO)>TIMING CHAIN ASSEMBLY>REMOVAL .
2. Rotate the camshaft by hand to compare the rotational resistances of the four shafts.
  NOTE:
  Compare rotational resistance with the camshaft in bank 1 and check the following items to see if there is any obvious fault such as unsmoothness of the camshaft in bank 2 and rotational resistance.
  - Foreign matter adhered to the camshaft
  - Damage to camshaft (scratch, scuffed, wear, etc.)
  - Check of influence of cam journal bearing not rotating properly
Is the check result OK?

Yes: Go to 13 .

No: Replace the cam carrier and the camshaft. Ref. to MECHANICAL (H4DO)>CAM CARRIER . Ref. to MECHANICAL (H4DO)>CAMSHAFT .

Go to 13 .
CHECK OIL PASSAGES BETWEEN OIL PUMP AND OIL CONTROL SOLENOID .
Visually check the following portions of oil passages connecting oil pump to intake oil control solenoid to see if there is any obvious fault such as adherence of foreign matter and clogging.
- Oil passage of the cam carrier
- Oil passage of the cylinder head side
- Oil passage from cam sprocket to camshaft connecting section
- Oil passage of the sprocket back side with the sprocket removed, and the camshaft end
NOTE: Refer to the removal procedure of cam carrier in the service information. Ref. to MECHANICAL (H4DO)>CAM CARRIER>REMOVAL .

Is the check result OK?

Yes: Replace the sprocket. Ref. to MECHANICAL (H4DO)>CAM SPROCKET>REMOVAL .
CAUTION:
- Excessive application of liquid gasket during assembly of the chain cover may cause malfunction. Use the type specified in the service information and apply appropriate amount (wire diameter). Ref. to MECHANICAL (H4DO)>CHAIN COVER>INSTALLATION .
- Push the oil filter until it becomes flush with the cam carrier surface. (Do not push excessively.) Ref. to MECHANICAL (H4DO)>CAM CARRIER>ASSEMBLY .
Go to 14 .

No: Remove the foreign matter. Replace the cam carrier oil filter. (Do not reuse it.)

Ref. to MECHANICAL (H4DO)>CAM CARRIER .
CAUTION:
- Excessive application of liquid gasket during assembly of the chain cover may cause malfunction. Use the type specified in the service information and apply appropriate amount (wire diameter). Ref. to MECHANICAL (H4DO)>CHAIN COVER>INSTALLATION .
- Push the oil filter until it becomes flush with the cam carrier surface. (Do not push excessively.) Ref. to MECHANICAL (H4DO)>CAM CARRIER>ASSEMBLY .
NOTE: After the procedure is finished, idle the engine for five minutes, and then replace (flush) the oil filter and engine oil. Ref. to LUBRICATION (H4DO)>ENGINE OIL . Ref. to LUBRICATION (H4DO)>ENGINE OIL FILTER .

Go to 14 .
CHECK ON-BOARD MONITOR TEST RESULTS .
1. Perform the Clear Memory Mode for the engine using the Subaru Select Monitor or a general scan tool. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>CLEAR MEMORY MODE .
2. Perform drive cycle T. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>DRIVE CYCLE .
3. Read values of "VVT Monitor Bank 1" and "VVT Monitor Bank 2" according to MODE $06 reading procedures using the Subaru Select Monitor or general scan tool. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>GENERAL SCAN TOOL>OPERATION>MODE $06 (REQUEST ON-BOARD MONITORING TEST RESULTS FOR CONTINUOUSLY MONITORED SYSTEMS) .
  CAUTION:
  - When performing driving cycle, there should be 2 persons (driver and checker) and the checker should perform the data check.
  - When performing the drive cycle on the public road, be very careful of the traffic condition and the safe driving must be the high priority.
  NOTE:
  - When the diagnostic value is 0, the diagnosis is incomplete. therefore, do not stop the engine and perform the drive cycle again.
  - Diagnostic values are updated repeatedly, and therefore, always check the data while diagnostic values are being read.
4. Record the read values in "VVT Monitor Bank 1" and "VVT Monitor Bank 2".
Is the value in "VVT Monitor Bank 2" 1000 or more?

Yes: Replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>ENGINE CONTROL MODULE (ECM) .

No: Go to 15.
CHECK CURRENT DATA .
Compare the values in "VVT Monitor Bank 1" and "VVT Monitor Bank 2" recorded in step 14.

Is the value in "VVT Monitor Bank 2" 1000 or less, and also larger than the value (value in "VVT Monitor Bank 1" x 1.5+100) compared to the value in "VVT Monitor Bank 1"?

Yes: Replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>ENGINE CONTROL MODULE (ECM) .

No: End.