Subaru Legacy BN/BS (2015-2019) Service Manual: General diagnostic table inspection

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h4do) / General diagnostic table inspection

1. ENGINE

NOTE:

Malfunction of parts other than those listed is also possible. Engine Trouble in General

Symptoms	Faulty parts
1. Engine stalls during idling.	1) Manifold absolute pressure sensor 2) Mass air flow and intake air temperature sensor 3) Ignition parts (1) 4) Engine coolant temperature sensor (2) 5) Crankshaft position sensor (3) 6) Camshaft position sensor (3) 7) Fuel injection parts (*4) 8) Electronic throttle control
2. Rough idling	1) Manifold absolute pressure sensor 2) Mass air flow and intake air temperature sensor 3) Engine coolant temperature sensor (2) 4) Ignition parts (1) 5) Air intake system (5) 6) Fuel injection parts (4) 7) Electronic throttle control 8) Crankshaft position sensor (3) 9) Camshaft position sensor (3) 10) Oxygen sensor 11) Fuel pump and fuel pump relay 12) EGR control valve
3. Engine does not return to idle.	1) Engine coolant temperature sensor 2) Electronic throttle control 3) Manifold absolute pressure sensor 4) Mass air flow and intake air temperature sensor 5) EGR control valve 6) Accelerator pedal position sensor 7) Engine oil temperature sensor
4. Poor acceleration	1) Manifold absolute pressure sensor 2) Mass air flow and intake air temperature sensor 3) Electronic throttle control 4) Fuel injection parts (4) 5) Fuel pump and fuel pump relay 6) Engine coolant temperature sensor (2) 7) Crankshaft position sensor (3) 8) Camshaft position sensor (3) 9) Engine torque control signal circuit 10) Ignition parts (*1) 11) EGR control valve 12) Accelerator pedal position sensor 13) Engine oil temperature sensor
5. Engine stalls, hesitates, or sputters at acceleration.	1) Manifold absolute pressure sensor 2) Mass air flow and intake air temperature sensor 3) Engine coolant temperature sensor (2) 4) Crankshaft position sensor (3) 5) Camshaft position sensor (3) 6) Purge control solenoid valve 7) Fuel injection parts (4) 8) Electronic throttle control 9) Fuel pump and fuel pump relay 10) EGR control valve
6. Surging	1) Mass air flow and intake air temperature sensor 2) Manifold absolute pressure sensor 3) Engine coolant temperature sensor (2) 4) Crankshaft position sensor (3) 5) Camshaft position sensor (3) 6) Fuel injection parts (4) 7) Electronic throttle control 8) Fuel pump and fuel pump relay 9) EGR control valve
7. Spark knock	1) Mass air flow and intake air temperature sensor 2) Manifold absolute pressure sensor 3) Engine coolant temperature sensor 4) Knock sensor 5) Fuel injection parts (*4) 6) Fuel pump and fuel pump relay 7) EGR control valve
8. After burning in exhaust system	1) Mass air flow and intake air temperature sensor 2) Manifold absolute pressure sensor 3) Engine coolant temperature sensor (2) 4) Fuel injection parts (4) 5) Fuel pump and fuel pump relay

*1: Check ignition coil and spark plug.

*2: Indicate the symptom occurring only in cold temperatures.

*3: Ensure the secure installation.

*4: Check fuel injector and fuel filter.

*5: Inspect air leak in air intake system.

Electrical component location location

1. CONTROL MODULE(1)Engine control module (ECM)(3)Malfunction indicator light(4)Delivery (test) mode fuse(2)Data link connector 2. SENSOR(1)Tumble generator valve actuators (with built-in opening a ...

General scan tool operation

1. HOW TO USE GENERAL SCAN TOOL1. Prepare a scan tool (general scan tool) required by SAE J1978.2. Connect the general scan tool to data link connector located in the lower portion of the instrument p ...

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