Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2021 Subaru WRX BaseFACTORY OEM SERVICE PROCEDURE
Section 18 (Engine Control System (Diagnostics) (2.5L) (2 Of 4))
WARNING: This page is about a different variant/trim than selected.
- Diagnostic Procedure with Diagnostic Trouble Code (DTC)
- DTC P0171: System Too Lean Bank 1
- DTC P0172: System Too Rich Bank 1
- DTC P0201: Cylinder 1 Injector "A" Circuit
- DTC P0202: Cylinder 2 Injector "A" Circuit
- DTC P0203: Cylinder 3 Injector "A" Circuit
- DTC P0204: Cylinder 4 Injector "A" Circuit
- DTC P0222: Throttle/Pedal Position Sensor/Switch "B" Circuit Low
- DTC P0223: Throttle/Pedal Position Sensor/Switch "B" Circuit High
- DTC P0230: Fuel Pump Primary Circuit
- DTC P0245: Turbocharger/Supercharger WASTEGATE Solenoid "A" Low
- DTC P0246: Turbocharger/Supercharger WASTEGATE Solenoid "A" High
- DTC P0300: Random/Multiple Cylinder Misfire Detected
- DTC P0301: Cylinder 1 Misfire Detected
- DTC P0302: Cylinder 2 Misfire Detected
- DTC P0303: Cylinder 3 Misfire Detected
- DTC P0304: Cylinder 4 Misfire Detected
- DTC P0327: Knock/Combustion Vibration Sensor 1 Circuit Low Bank 1 Or Single Sensor
- DTC P0328: Knock/Combustion Vibration Sensor 1 Circuit High Bank 1 Or Single Sensor
- DTC P0335: Crankshaft Position Sensor "A" Circuit
- DTC P0336: Crankshaft Position Sensor "A" Circuit Range/Performance
- DTC P0340: Camshaft Position Sensor "A" Circuit Bank 1 Or Single Sensor
- DTC P0341: Camshaft Position Sensor "A" Circuit Range/Performance Bank 1 Or Single Sensor
- DTC P0345: Camshaft Position Sensor "A" Circuit Bank 2
- DTC P0346: Camshaft Position Sensor "A" Circuit Range/Performance Bank 2
- DTC P0351: Ignition Coil "A" Primary Control Circuit/Open
- DTC P0352: Ignition Coil "B" Primary Control Circuit/Open
- DTC P0353: Ignition Coil "C" Primary Control Circuit/Open
- DTC P0354: Ignition Coil "D" Primary Control Circuit/Open
- DTC P0365: Camshaft Position Sensor "B" Circuit Bank 1
- DTC P0366: Camshaft Position Sensor "B" Circuit Range/Performance Bank 1
- DTC P0390: Camshaft Position Sensor "B" Circuit Bank 2
- DTC P0391: Camshaft Position Sensor "B" Circuit Range/Performance Bank 2
- DTC P0410: Secondary Air System
- DTC P0411: Secondary Air System Incorrect Flow Detected
- DTC P0413: Secondary Air System Switching Valve "A" Circuit Open
- DTC P0414: Secondary Air System Switching Valve "A" Circuit Shorted
- DTC P0416: Secondary Air System Switching Valve "B" Circuit Open
- DTC P0417: Secondary Air System Switching Valve "B" Circuit Shorted
- DTC P0420: Catalyst System Efficiency Below Threshold Bank 1
- DTC P0441: EVAP System (CPC) Incorrect Purge Flow
- DTC P0455: EVAP System (CPC) Leak Detected (Large Leak)
- DTC P0456: EVAP System (CPC) Leak Detected (Very Small Leak)
- DTC P0458: EVAP System (CPC) Purge Control Valve "A" Circuit Low
- DTC P0459: EVAP System (CPC) Purge Control Valve "A" Circuit High
- DTC P0461: Fuel Level Sensor "A" Circuit Range/Performance
- DTC P0462: Fuel Level Sensor "A" Circuit Low
- DTC P0463: Fuel Level Sensor "A" Circuit High
- DTC P04AC: EVAP System (CPC) Purge Control Valve "B" Circuit Low
- DTC P04AD: EVAP System (CPC) Purge Control Valve "B" Circuit High
- DTC P04AF: EVAP System Purge Control Valve (CPC) "B" Stuck Closed
- DTC P04DB: Crankcase Ventilation System (PCV) Disconnected
- DTC P04F0: EVAP System High Pressure Purge Line (CPC2) Performance
- DTC P0500: Vehicle Speed Sensor "A" Circuit
- DTC P0506: Idle Control System Rpm - Lower Than Expected
- DTC P0507: Idle Control System Rpm - Higher Than Expected
- DTC P050A: Cold Start Idle Control System Performance
- DTC P050B: Cold Start Ignition Timing Performance
- DTC P0512: Starter (Switch) Request Circuit
- DTC P0560: System Voltage
- DTC P0604: Internal Control Module Random Access Memory (Ram) Error
- DTC P0605: Internal Control Module Read Only Memory (ROM) Error
- DTC P0606: Control Module Processor
- DTC P060A: Internal Control Module Monitoring Processor Performance
- DTC P060B: Internal Control Module A/D Processing Performance
- DTC P0616: Starter Relay "A" Circuit Low
- DTC P0617: Starter Relay "A" Circuit High
- DTC P062F: Internal Control Module EEPROM Error
- DTC P0685: ECM/Pcm Power Relay Control Circuit/Open
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.