DTC P050A: Cold Start Idle Control System Performance: Notes

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:

Engine keeps running at higher speed than specified idle speed.
Engine keeps running at a lower speed than the specified idle speed.
Engine stall

Failure detection pattern:

"Primary" (high-priority diagnosis)

Warning light/indicator light:

Malfunction indicator light

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM>2.0 L MODEL .

Courtesy of SUBARU OF AMERICA, INC.

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

BASIC INSPECTION .
Before performing the diagnosis, perform basic inspection. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0)>GENERAL DESCRIPTION>INSPECTION .
NOTE:
- Check the battery and its installation condition.
- Check the related fuse.
- Visually check that the related connectors are properly connected.
  Also, check the related ground terminal for looseness and corrosion.
Is the check result OK?

Yes : GO TO 2.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC other than P050A displayed? (Current code)

Yes : Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0)>DIAGNOSTIC TROUBLE CODE (DTC) .

No : GO TO 3.
CHECK ENGINE OIL .
1. Turn the ignition switch to OFF.
2. Check the engine oil amount. Ref. to LUBRICATION (H4DO)>ENGINE OIL .
Is there a proper amount of engine oil?

Yes : GO TO 4.

No : Replace engine oil. Ref. to LUBRICATION (H4DO)>ENGINE OIL .

After replacement, GO TO 31.
CHECK EXHAUST SYSTEM .
Check exhaust system parts.

Are there holes or loose bolts on exhaust system?

Yes : Repair the exhaust system. Ref. to EXHAUST (H4DO)>GENERAL DESCRIPTION .

After the repair, GO TO 31.

No : GO TO 5.
CHECK AIR INTAKE SYSTEM .
Check the installing condition of the air intake system.

Are there holes, loose bolts or disconnection of hose on air intake system?

Yes : Repair the air intake system. Ref. to INTAKE (INDUCTION) (H4DO)>GENERAL DESCRIPTION .

After the repair, GO TO 31.

No : GO TO 6.
CHECK FUEL PRESSURE .
WARNING: Place "NO OPEN FLAMES" signs near the working area.
CAUTION:
- Be careful not to spill fuel.
- Before attaching/detaching a fuel pressure gauge, release the fuel pressure.
Check the fuel pressure. Ref. to MECHANICAL (H4DO)>FUEL PRESSURE>INSPECTION .

Is the check result OK?

Yes : GO TO 7.

No : Check the fuel pump and fuel delivery line. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL PUMP ASSEMBLY>INSPECTION . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL DELIVERY AND EVAPORATION LINES>INSPECTION .
CHECK ENGINE COOLANT TEMPERATURE SENSOR .
1. Start the engine and warm up completely.
2. Using the Subaru Select Monitor, read the value in [Engine Coolant Temperature].
  NOTE: For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR .
  
  Standard: The value of [Engine Coolant Temperature] is 75°C (167°F) or more .
Is the check result OK?

Yes : GO TO 8.

No : Replace the engine coolant temperature sensor (outlet). Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>ENGINE COOLANT TEMPERATURE SENSOR .

After replacement, GO TO 31.
CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .
1. Place the select lever in "P" range or "N" range.
2. Turn the A/C switch to OFF.
3. Turn all the accessory switches to OFF.
4. Using the Subaru Select Monitor, read the value in [Mass Air Flow].
  NOTE: For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR .
  
  Standard: The value of [Mass Air Flow] is 2 - 5 g/s (0.26 - 0.66 lb/min) .
Is the check result OK?

Yes : GO TO 9.

No : Replace the mass air flow and intake air temperature sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .

After replacement, GO TO 31.
CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .
1. Place the select lever in "P" range or "N" range.
2. Turn the A/C switch to OFF.
3. Turn all the accessory switches to OFF.
4. Open the front hood.
5. Measure the ambient temperature.
6. Using the Subaru Select Monitor, read the value in [Intake Air Temp.].
  NOTE: For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR .
  
  Standard: The value obtained by subtracting ambient temperature from [Intake Air Temp.] is -10 - 50°C (-18 - 90°F) .
Is the check result OK?

Yes : GO TO 10.

No : Replace the mass air flow and intake air temperature sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .

After replacement, GO TO 31.
CHECK HARNESS (SHORT TO GROUND IN FUEL INJECTOR) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
3. Move the A/C compressor aside so that it does not interfere with the work. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR .
  NOTE: This procedure is required to disconnect the fuel injector #2 connector.
4. Disconnect the connector from fuel injector on faulty cylinders.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
5. Measure the resistance between the following terminals of the faulty cylinder.
  Connector & terminal: Standard
  
  #1 (E101) No. 1 - Chassis ground: 10 KΩ or more
  
  #1 (E101) No. 2 - Chassis ground: 10 KΩ or more
  
  #2 (E102) No. 1 - Chassis ground: 10 KΩ or more
  
  #2 (E102) No. 2 - Chassis ground: 10 KΩ or more
  
  #3 (E103) No. 1 - Chassis ground: 10 KΩ or more
  
  #3 (E103) No. 2 - Chassis ground: 10 KΩ or more
  
  #4 (E104) No. 1 - Chassis ground: 10 KΩ or more
  
  #4 (E104) No. 2 - Chassis ground: 10 KΩ or more
Is the check result OK?

Yes : GO TO 11.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (OPEN CIRCUIT BETWEEN ECM AND FUEL INJECTOR) .
Measure the resistance between the following terminals of the faulty cylinder.

Connector & terminal: Standard

#1 (E53) No. 96 - (E101) No. 1: Less than 1 Ω

#1 (E53) No. 87 - (E101) No. 2: Less than 1 Ω

#2 (E53) No. 95 - (E102) No. 1: Less than 1 Ω

#2 (E53) No. 86 - (E102) No. 2: Less than 1 Ω

#3 (E53) No. 93 - (E103) No. 1: Less than 1 Ω

#3 (E53) No. 84 - (E103) No. 2: Less than 1 Ω

#4 (E53) No. 94 - (E104) No. 1: Less than 1 Ω

#4 (E53) No. 85 - (E104) No. 2: Less than 1 Ω

Is the check result OK?

Yes : GO TO 12.

No : Repair the defective part.
NOTE:
In this case, repair the following item:
- Open circuit in harness between ECM and fuel injector connector
- Poor contact of coupling connector
After the repair, GO TO 31.
CHECK FUEL INJECTOR .
Check the fuel injector on faulty cylinder. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR>INSPECTION .

Is the check result OK?

Yes : GO TO 13.

No : Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL INJECTOR .

After replacement, GO TO 31.
CHECK INSTALLATION CONDITION OF CAMSHAFT POSITION SENSOR AND CRANKSHAFT POSITION SENSOR .
Check the installation condition of the camshaft position sensor and crankshaft position sensor.

Is the camshaft position sensor or crankshaft position sensor loosely installed?

Yes : Tighten the camshaft position sensor or crankshaft position sensor.

Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CAMSHAFT POSITION SENSOR . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CRANKSHAFT POSITION SENSOR .

After operation, GO TO 31.

No : GO TO 14.
CHECK CRANKSHAFT POSITION SENSOR PLATE .
Check the crankshaft position sensor plate. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CRANKSHAFT POSITION SENSOR PLATE>INSPECTION .

Is the crankshaft position sensor plate rusted or does it have broken teeth?

Yes : Replace the crankshaft position sensor plate. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>CRANKSHAFT POSITION SENSOR PLATE .

After replacement, GO TO 31.

No : GO TO 15.
CHECK INSTALLATION CONDITION OF TIMING CHAIN .
Turn the crankshaft using the Subaru ST, and align the alignment mark on crank sprocket with alignment mark on cylinder block.

Subaru ST 18252AA000 CRANKSHAFT SOCKET

Is the timing chain dislocated from its proper position?

Yes : Correct the installation condition of timing chain. Ref. to MECHANICAL (H4DO)>TIMING CHAIN ASSEMBLY .

After the repair, GO TO 31.

No : GO TO 16.
CHECK HARNESS (GROUND SHORT CIRCUIT BETWEEN ECM AND ENGINE GROUND) .
1. Disconnect the connector from ECM.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
2. Disconnect the connectors from electronic throttle control.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
3. Measure the resistance between the following terminals.
  Connector & terminal: Standard
  
  (E53) No. 27 - Chassis ground: 10 KΩ or more
  
  (E53) No. 29 - Chassis ground: 10 KΩ or more
  
  (E53) No. 29 - (E53) No. 44: 10 KΩ or more
  
  (E53) No. 43 - Chassis ground: 10 KΩ or more
  
  (E53) No. 43 - (E53) No. 44: 10 KΩ or more
Is the check result OK?

Yes : GO TO 17.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (GROUND SHORT CIRCUIT BETWEEN ELECTRONIC THROTTLE CONTROL AND ENGINE GROUND) .
1. Connect the connector to ECM.
2. Measure the resistance between the following terminals.
  Connector & terminal: Standard
  
  (E116) No. 4 - Chassis ground: 10 KΩ or more
  
  (E116) No. 6 - Chassis ground: 10 KΩ or more
Is the check result OK?

Yes : GO TO 18.

No : Repair the ground short circuit of harness between ECM connector and electronic throttle control connector. Replace the ECM if defective. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>ENGINE CONTROL MODULE (ECM) .

After operation, GO TO 31.
CHECK HARNESS (OPEN CIRCUIT BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL) .
1. Disconnect the connector from ECM.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
2. Measure the resistance between the following terminals.
  Connector & terminal: Standard
  
  (E53) No. 29 - (E116) No. 6: Less than 1 Ω
  
  (E53) No. 30 - (E116) No. 3: Less than 1 Ω
  
  (E53) No. 43 - (E116) No. 4: Less than 1 Ω
Is the check result OK?

Yes : GO TO 19.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (OPEN CIRCUIT BETWEEN ELECTRONIC THROTTLE CONTROL AND ENGINE GROUND) .
1. Connect the connector to ECM.
2. Measure the resistance between the following terminals.
  Connector & terminal: Standard
  
  (E116) No. 3 - Chassis ground: Less than 5 Ω
Is the check result OK?

Yes : GO TO 20.

No : Repair the defective part.
NOTE:
In this case, repair the following item:
- Open circuit of harness between ECM connector and engine ground
- Poor contact of ECM connector
- Poor contact of coupling connector
After the repair, GO TO 31.
CHECK HARNESS (SHORT TO POWER SUPPLY BETWEEN ELECTRONIC THROTTLE CONTROL AND ENGINE GROUND) .
1. Turn the ignition switch to ON. (Engine OFF)
2. Measure the voltage between the following terminals.
  Connector & terminal: Standard
  
  (E116) No. 4 (+) - Chassis ground (-): Less than 5 V
  
  (E116) No. 6 (+) - Chassis ground (-): Less than 5 V
Is the check result OK?

Yes : GO TO 21.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (SHORT BETWEEN LINES BETWEEN ECM CONNECTORS) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
3. Measure the resistance between the following terminals.
  Connector & terminal: Standard
  
  (E53) No. 27 - (E53) No. 29: 10 KΩ or more
  
  (E53) No. 27 - (E53) No. 43: 10 KΩ or more
Is the check result OK?

Yes : GO TO 22.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK SENSOR OUTPUT .
1. Connect all connectors.
2. Turn the ignition switch to ON. (Engine OFF)
3. Using the Subaru Select Monitor, read the value in [Main-Throttle Sensor].
  NOTE: For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR .
  
  Standard: The value of [Main-Throttle Sensor] is 0.81 - 0.87 V .
Is the check result OK?

Yes : GO TO 23.

No : Repair the poor contact of electronic throttle control connector. Replace the electronic throttle control if defective. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>THROTTLE BODY .

After operation, GO TO 31.
CHECK SENSOR OUTPUT .
Using the Subaru Select Monitor, read the value in [Sub-Throttle Sensor].

NOTE: For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR .

Standard: The value of [Sub-Throttle Sensor] is 1.64 - 1.7 V .

Is the check result OK?

Yes : GO TO 24.

No : Repair the poor contact of electronic throttle control connector. Replace the electronic throttle control if defective. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>THROTTLE BODY .

After operation, GO TO 31.
CHECK HARNESS (OPEN CIRCUIT BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
3. Disconnect the connectors from electronic throttle control.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
4. Measure the resistance between the following terminals.
  Connector & terminal: Standard
  
  (E53) No. 30 - (E116) No. 3: Less than 1 Ω
  
  (E53) No. 43 - (E116) No. 4: Less than 1 Ω
  
  (E53) No. 29 - (E116) No. 6: Less than 1 Ω
Is the check result OK?

Yes : GO TO 25.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (SHORT TO POWER SUPPLY IN ELECTRONIC THROTTLE CONTROL) .
1. Connect the connector to ECM.
2. Turn the ignition switch to ON. (Engine OFF)
3. Measure the voltage between the following terminals.
  Connector & terminal: Standard
  
  (E116) No. 1 (+) - Chassis ground (-): Less than 5 V
  
  (E116) No. 2 (+) - Chassis ground (-): Less than 5 V
Is the check result OK?

Yes : GO TO 26.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (SHORT TO GROUND IN ELECTRONIC THROTTLE CONTROL) .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
  CAUTION: When disconnecting the connector, check for poor contact due to damage, looseness, adherence of foreign matter on the connector and terminal.
3. Measure the resistance between the following terminals.
  Connector & terminal: Standard
  
  (E116) No. 1 - Chassis ground: 10 KΩ or more
  
  (E116) No. 2 - Chassis ground: 10 KΩ or more
Is the check result OK?

Yes : GO TO 27.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (SHORT CIRCUIT BETWEEN LINES IN ELECTRONIC THROTTLE CONTROL CONNECTOR) .
Measure the resistance between the following terminals.

Connector & terminal: Standard

(E116) No. 1 - (E116) No. 2: 10 KΩ or more

Is the check result OK?

Yes : GO TO 28.

No : Repair the defective part.

After the repair, GO TO 31.
CHECK HARNESS (OPEN CIRCUIT IN ECM) .
Measure the resistance between the following terminals.

Connector & terminal: Standard

(B62) No. 69 - Chassis ground: Less than 5 Ω

(B62) No. 70 - Chassis ground: Less than 5 Ω

(B62) No. 71 - Chassis ground: Less than 5 Ω

(B62) No. 72 - Chassis ground: Less than 5 Ω

Is the check result OK?

Yes : GO TO 29.

No : Repair the defective part.
NOTE:
In this case, repair the following item:
- Open circuit of harness between ECM connector and engine ground
- Poor contact of coupling connector
After the repair, GO TO 31.
CHECK ELECTRONIC THROTTLE CONTROL .
Measure the resistance between the following terminals.

Terminal: Standard

No. 1 - No. 2: 50 Ω or less

Is the check result OK?

Yes : GO TO 30.

No : Replace the electronic throttle control. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>THROTTLE BODY .

After replacement, GO TO 31.
CHECK ELECTRONIC THROTTLE CONTROL .
1. Move the throttle valve to the fully opened and fully closed positions with fingers.
2. Check that the valve returns to the specified position when releasing fingers.
  Specification:
  
  3 mm (0.12 in) from fully closed position
Is the check result OK?

Yes : Repair the poor contact of ECM connector.

After the repair, GO TO 31.

No : Replace the electronic throttle control. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>THROTTLE BODY .

After replacement, GO TO 31.
CHECK REPAIR .
1. Perform the inspection mode corresponding to DTC. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0)>INSPECTION MODE>PROCEDURE .
2. Confirm that DTC or cancel code is not stored and the malfunction is eliminated.
Is the check result OK?

Yes : Finish the diagnosis.

No : Perform the diagnosis according to the basic diagnostic procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .