DTC P050A Cold Start Idle Control System Performance: Notes

WARNING: This page is about a different variant/trim than selected.

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 stalls.

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Clear Memory Mode . and Inspection Mode Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Inspection Mode .
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 .

Fig 1: Cold Start Idle Control System - Wiring Diagram (1 Of 2)

Courtesy of SUBARU OF AMERICA, INC.

Fig 2: Cold Start Idle Control System - Wiring Diagram (2 Of 2)

Courtesy of SUBARU OF AMERICA, INC.

CHECK FOR ANY OTHER DTC ON DISPLAY .
Is any other DTC displayed?
- Yes: Check the appropriate DTC using the "List of Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>List of Diagnostic Trouble Code (DTC) .
- No: Go to 2 .
CHECK ENGINE OIL .
Is there a proper amount of engine oil?
- Yes: Go to 3 .
- No: Replace engine oil. Ref. to LUBRICATION(H4DO)>Engine Oil>REPLACEMENT .
CHECK EXHAUST SYSTEM .
Are there holes or loose bolts on exhaust system?
- Yes: Repair the exhaust system.
- No: Go to 4 .
CHECK AIR INTAKE SYSTEM .
Are there holes, loose bolts or disconnection of hose on air intake system?
- Yes: Repair the air intake system.
- No: Go to 5 .
CHECK FUEL PRESSURE .
WARNING: Place "NO OPEN FLAMES" signs near the working area.

CAUTION: Be careful not to spill fuel.

Measure the fuel pressure. Ref. to MECHANICAL(H4DO)>Fuel Pressure>INSPECTION .

CAUTION: Release fuel pressure before removing the fuel pressure gauge.

Is the measured value 340 - 400 kPa (3.5 - 4.1 kg/cm² , 49 - 58 psi)?
- Yes: Go to 6 .
- No: Check the fuel pump and fuel delivery line. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Fuel Pump>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 or a general scan tool, read the value of [Coolant Temp.].
NOTE:
- Subaru Select Monitor
  For detailed procedures, refer to "Data Monitor". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Subaru Select Monitor .
- General scan tool
  For detailed operation procedures, refer to the general scan tool operation manual.
Is the value of [Coolant Temp.] 75°C (167°F) or more?
- Yes: Go to 7 .
- No: Replace the engine coolant temperature sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Engine Coolant Temperature Sensor .
CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .
1. Start the engine and warm up engine until coolant temperature is higher than 75°C (167°F).
2. For CVT models, set the select lever to "P" range or "N" range, and for MT models, place the shift lever in the neutral position.
3. Turn the A/C switch to OFF.
4. Turn all the accessory switches to OFF.
5. Using the Subaru Select Monitor or a general scan tool, read the value of [Air Flow Rate from Mass Air Flow Sensor].
NOTE:
- Subaru Select Monitor
  For detailed procedures, refer to "Data Monitor". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Subaru Select Monitor .
- General scan tool
  For detailed operation procedures, refer to the general scan tool operation manual.
Is the value of [Air Flow Rate from Mass Air Flow Sensor] 2.0 - 5.0 g/s (0.26 - 0.66 lb/m)?
- Yes: Go to 8 .
- 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 .
CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .
1. Start the engine and warm up engine until coolant temperature is higher than 75°C (167°F).
2. For CVT models, set the select lever to "P" range or "N" range, and for MT models, place the shift lever in the neutral position.
3. Turn the A/C switch to OFF.
4. Turn all the accessory switches to OFF.
5. Open the front hood.
6. Measure the ambient temperature.
7. Using the Subaru Select Monitor or a general scan tool, read the value of [Intake Air Temp.].
NOTE:
- Subaru Select Monitor
  For detailed procedures, refer to "Data Monitor". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Subaru Select Monitor .
- General scan tool
  For detailed operation procedures, refer to the general scan tool operation manual.
Subtract ambient temperature from [Intake Air Temp.]. Is the obtained value -10 - 50°C (-18 - 90°F)?
- Yes: Go to 9 .
- No: Check the mass air flow and intake air temperature sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Mass Air Flow and Intake Air Temperature Sensor .
CHECK OUTPUT SIGNAL OF ECM .
1. Turn the ignition switch to ON.
2. Measure the voltage between ECM and chassis ground on faulty cylinders.
Connector & terminal

#1 (B135) No. 23 (+) - Chassis ground (-):

#2 (B135) No. 8 (+) - Chassis ground (-):

#3 (B135) No. 9 (+) - Chassis ground (-):

#4 (B135) No. 22 (+) - Chassis ground (-):

Is the voltage 10 V or more?
- Yes: Go to 14.
- No: Go to 10 .
CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from fuel injector on faulty cylinders.
3. Measure the resistance between fuel injector connector and engine ground on faulty cylinders.
Connector & terminal

#1 (E5) No. 1 - Engine ground:

#2 (E16) No. 1 - Engine ground:

#3 (E6) No. 1 - Engine ground:

#4 (E17) No. 1 - Engine ground:

Is the resistance 1 MΩ or more?
- Yes: Go to 11 .
- No: Repair the short circuit to ground in harness between ECM connector and fuel injector connector.
CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR .
Measure the resistance of harness between ECM and fuel injector connector on faulty cylinders.

Connector & terminal

#1 (B135) No. 23 - (E5) No. 1:

#2 (B135) No. 8 - (E16) No. 1:

#3 (B135) No. 9 - (E6) No. 1:

#4 (B135) No. 22 - (E17) No. 1:

Is the resistance less than 1 Ω?
- Yes: Go to 12 .
- No: repair the harness and connector.
  NOTE:
  In this case, repair the following item:
  - Open circuit in harness between ECM connector and fuel injector connector
  - Poor contact of coupling connector
CHECK FUEL INJECTOR .
Measure the resistance between fuel injector terminals on faulty cylinder.

Terminals

No. 1 -No. 2:

Is the resistance 5 - 20 Ω?
- Yes: Go to 13 .
- No: Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Fuel Injector .
CHECK POWER SUPPLY LINE .
1. Turn the ignition switch to ON.
2. Measure the voltage between fuel injector and engine ground on faulty cylinders.
Connector & terminal

#1 (E5) No. 2 (+) - Engine ground (-):

#2 (E16) No. 2 (+) - Engine ground (-):

#3 (E6) No. 2 (+) - Engine ground (-):

#4 (E17) No. 2 (+) - Engine ground (-):

Is the voltage 10 V or more?
- Yes: Repair the poor contact of all connectors in fuel injector circuit.
- No: repair the harness and connector.
  NOTE:
  In this case, repair the following item:
  - Open circuit in harness between the main relay connector and fuel injector connector on faulty cylinders
  - Poor contact of coupling connector
  - Poor contact of main relay connector
CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from fuel injector on faulty cylinders.
3. Turn the ignition switch to ON.
4. Measure the voltage between ECM and chassis ground on faulty cylinders.
Connector & terminal

#1 (B135) No. 23 (+) - Chassis ground (-):

#2 (B135) No. 8 (+) - Chassis ground (-):

#3 (B135) No. 9 (+) - Chassis ground (-):

#4 (B135) No. 22 (+) - Chassis ground (-):

Is the voltage 10 V or more?
- Yes: Repair the short circuit to power in harness between ECM connector and fuel injector.
- No: Go to 15 .
CHECK FUEL INJECTOR .
1. Turn the ignition switch to OFF.
2. Measure the resistance between fuel injector terminals on faulty cylinder.
Terminals

No. 1 -No. 2:

Is the resistance 5 - 20 Ω?
- Yes: Go to 16 .
- No: Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Fuel Injector .
CHECK INSTALLATION CONDITION OF CAMSHAFT POSITION SENSOR/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>INSTALLATION . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Crankshaft Position Sensor>INSTALLATION .
- No: Go to 17 .
CHECK CRANKSHAFT POSITION SENSOR PLATE .
Is the crankshaft position sensor plate rusted or does it have broken teeth?
- Yes: Replace the crankshaft position sensor plate. Ref. to MECHANICAL(H4DO)>Cylinder Block .
- No: Go to 18 .
CHECK INSTALLATION CONDITION OF TIMING CHAIN .
Turn the crankshaft using ST, and align the alignment mark on crank sprocket with alignment mark on cylinder block.

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 .
- No: Go to 19 .
CHECK ELECTRONIC THROTTLE CONTROL RELAY .
1. Turn the ignition switch to OFF.
2. Remove the electronic throttle control relay.
3. Connect the battery to terminals No. 16 and No. 17 of electronic throttle control relay.
4. Measure the resistance between electronic throttle control relay terminals.
Terminals

No. 14 -No. 15:

Is the resistance less than 1 Ω?
- Yes: Go to 20 .
- No: Replace the electronic throttle control relay. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Electronic Throttle Control Relay .
CHECK POWER SUPPLY OF ELECTRONIC THROTTLE CONTROL RELAY .
Measure the voltage between electronic throttle control relay connector and chassis ground.

Connector & terminal

(B225) No. 15 (+) - Chassis ground (-):

Is the voltage 10 V or more?
- Yes: Go to 21 .
- No: Repair the open or short to ground in the power supply circuit.
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL RELAY CONNECTOR .
1. Disconnect the connector from ECM.
2. Turn the ignition switch to ON.
3. Measure the voltage between electronic throttle control relay connector and chassis ground.
Connector & terminal

(B225) No. 17 (+) - Chassis ground (-):

Is the voltage 10 V or more?
- Yes: Repair the short circuit to power in the harness between ECM connector and electronic throttle control relay connector.
- No: Go to 22 .
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL RELAY CONNECTOR .
1. Turn the ignition switch to OFF.
2. Measure the resistance between electronic throttle control relay connector and chassis ground.
Connector & terminal

(B225) No. 14 - Chassis ground:

(B225) No. 17 - Chassis ground:

Is the resistance 1 MΩ or more?
- Yes: Go to 23 .
- No: Repair the short circuit to ground in harness between ECM connector and electronic throttle control relay connector.
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL RELAY CONNECTOR .
Measure the resistance of harness between ECM connector and electronic throttle control relay connector.

Connector & terminal

(B134) No. 65 - (B225) No. 17:

(B134) No. 13 - (B225) No. 14:

Is the resistance less than 1 Ω?
- Yes: Go to 24 .
- No: Repair the open circuit in harness between ECM connector and electronic throttle control relay connector.
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connectors from electronic throttle control.
3. Disconnect the connector from ECM.
4. Measure the resistance between ECM connector and chassis ground.
Connector & terminal

(B135) No. 32 - Chassis ground:

(B135) No. 29 - Chassis ground:

(B135) No. 29 - (B135) No. 65:

(B135) No. 31 - Chassis ground:

(B135) No. 31 - (B135) No. 65:

Is the resistance 1 MΩ or more?
- Yes: Go to 25 .
- No: Repair the ground short circuit of harness between ECM connector and electronic throttle control connector.
CHECK SHORT CIRCUIT INSIDE THE ECM .
1. Connect the connector to ECM.
2. Measure the resistance between electronic throttle control connector and engine ground.
Connector & terminal

(E57) No. 6 - Engine ground:

(E57) No. 4 - Engine ground:

Is the resistance 1 MΩ or more?
- Yes: Go to 26 .
- 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) .
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Disconnect the connector from ECM.
2. Measure the resistance of harness between ECM connector and electronic throttle control connector.
Connector & terminal

(B135) No. 29 - (E57) No. 6:

(B135) No. 31 - (E57) No. 4:

(B135) No. 34 - (E57) No. 3:

Is the resistance less than 1 Ω?
- Yes: Go to 27 .
- No: repair the harness and connector.
  NOTE:
  In this case, repair the following item:
  - Open circuit in harness between ECM connector and electronic throttle control connector
  - Poor contact of coupling connector
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Connect the connector to ECM.
2. Measure the resistance between electronic throttle control connector and engine ground.
Connector & terminal

(E57) No. 3 - Engine ground:

Is the resistance less than 5 Ω?
- Yes: Go to 28 .
- No: repair the harness and connector.
  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
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Turn the ignition switch to ON.
2. Measure the voltage between electronic throttle control connector and engine ground.
Connector & terminal

(E57) No. 6 (+) - Engine ground (-):

(E57) No. 4 (+) - Engine ground (-):

Is the voltage 5 V or more?
- Yes: Repair the short circuit to power in the harness between ECM connector and electronic throttle control connector.
- No: Go to 29 .
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Measure the resistance between ECM connectors.
  Connector & terminal
  
  (B135) No. 32 - (B135) No. 29:
  
  (B135) No. 32 - (B135) No. 31:
Is the resistance 1 MΩ or more?
- Yes: Go to 30 .
- No: Repair the short circuit to power in the harness between ECM connector and electronic throttle control connector.
CHECK SENSOR OUTPUT .
1. Connect all connectors.
2. Turn the ignition switch to ON.
3. Using the Subaru Select Monitor, read the value in [Main-Throttle Sensor].
  NOTE: For detailed procedures, refer to "Data Monitor". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Subaru Select Monitor .
Is the value of [Main-Throttle Sensor] 0.81 - 0.87 V?
- Yes: Go to 31 .
- 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 .
CHECK SENSOR OUTPUT .
Using the Subaru Select Monitor, read the value in [Sub-Throttle Sensor].

NOTE: For detailed procedures, refer to "Data Monitor". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Subaru Select Monitor .

Is the value of [Sub-Throttle Sensor] 1.64 - 1.70 V?
- Yes: Go to 32 .
- 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 .
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connectors from electronic throttle control.
3. Disconnect the connector from ECM.
4. Measure the resistance between ECM connector and electronic throttle control connector.
Connector & terminal

(B135) No. 14 - (E57) No. 2:

(B135) No. 1 - (E57) No. 1:

Is the resistance less than 1 Ω?
- Yes: Go to 33 .
- No: repair the harness and connector.
  NOTE:
  In this case, repair the following item:
  - Open circuit in harness between ECM connector and electronic throttle control connector
  - Poor contact of coupling connector
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Connect the connector to ECM.
2. Turn the ignition switch to ON.
3. Measure the voltage between electronic throttle control connector and engine ground.
Connector & terminal

(E57) No. 2 (+) - Engine ground (-):

(E57) No. 1 (+) - Engine ground (-):

Is the voltage 5 V or more?
- Yes: Repair the short circuit to power in the harness between ECM connector and electronic throttle control connector.
- No: Go to 34 .
CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Measure the resistance between electronic throttle control connector and engine ground.
Connector & terminal

(E57) No. 2 - Engine ground:

(E57) No. 1 - Engine ground:

Is the resistance 1 MΩ or more?
- Yes: Go to 35 .
- No: Repair the ground short circuit of harness between ECM connector and electronic throttle control connector.
CHECK HARNESS BETWEEN ELECTRONIC THROTTLE CONTROL CONNECTOR .
Measure the resistance between electronic throttle control connectors.

Connector & terminal

(E57) No. 2 - (E57) No. 1:

Is the resistance 1 MΩ or more?
- Yes: Go to 36 .
- No: Repair the short circuit in harness between ECM connector and electronic throttle control connector.
CHECK ELECTRONIC THROTTLE CONTROL GROUND CIRCUIT .
Measure the resistance between ECM connector and chassis ground.

Connector & terminal

(B135) No. 61 - Chassis ground:

(B135) No. 62 - Chassis ground:

(B135) No. 63 - Chassis ground:

(B135) No. 64 - Chassis ground:

(B135) No. 65 - Chassis ground:

Is the resistance less than 5 Ω?
- Yes: Go to 37 .
- No: repair the harness and connector.
  NOTE:
  In this case, repair the following item:
  - Open circuit of harness between ECM connector and engine ground
  - Poor contact of coupling connector
CHECK ELECTRONIC THROTTLE CONTROL .
Measure the resistance between electronic throttle control terminals.

Terminals

No. 2 -No. 1:

Is the resistance 50 Ω or less?
- Yes: Go to 38 .
- No: Replace the electronic throttle control. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Throttle Body .
CHECK ELECTRONIC THROTTLE CONTROL .
Move the throttle valve to the fully opened and fully closed positions with fingers.

Check that the valve returns to the specified position when releasing fingers.

Does the valve return to the specified position? Standard value: 3 mm (0.12 in) from fully closed position
- Yes: Repair the poor contact of ECM connector.
- No: Replace the electronic throttle control. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>Throttle Body .