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.
2018 Subaru WRX STIFACTORY OEM SERVICE PROCEDURE
Engine Control System (Diagnostics) (4 Of 4) (STI)
- Diagnostic Procedure with Diagnostic Trouble Code (DTC)
- DTC P2101: Throttle Actuator "A" Control Motor Circuit Range/Performance
- DTC P2102: Throttle Actuator "A" Control Motor Circuit Low
- DTC P2103: Throttle Actuator "A" Control Motor Circuit High
- DTC P2109: Throttle/Pedal Position Sensor "A" Minimum Stop Performance
- DTC P2119: Throttle Actuator "A" Control Throttle Body Range/Performance
- DTC P2122: Throttle/Pedal Position Sensor/Switch "D" Circuit Low
- DTC P2123: Throttle/Pedal Position Sensor/Switch "D" Circuit High
- DTC P2127: Throttle/Pedal Position Sensor/Switch "E" Circuit Low
- DTC P2128: Throttle/Pedal Position Sensor/Switch "E" Circuit High
- DTC P2135: Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation
- DTC P2138: Throttle/Pedal Position Sensor/Switch "D"/"E" Voltage Correlation
- DTC P2195: A/F/O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1
- DTC P2196: A/F/O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 1
- DTC P219A: Bank 1 Air-Fuel Ratio Imbalance
- DTC P2257: Secondary Air System Control "A" Circuit Low
- DTC P2258: Secondary Air System Control "A" Circuit High
- DTC P2270: O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2
- DTC P2271: O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2
- DTC P2401: EVAP System Leak Detection Pump Control Circuit Low
- DTC P2402: EVAP System Leak Detection Pump Control Circuit High
- DTC P2404: EVAP System Leak Detection Pump Sense Circuit Range/Performance
- DTC P2419: EVAP System Switching Valve Control Circuit Low
- DTC P2420: EVAP System Switching Valve Control Circuit High
- DTC P2431: Secondary Air System Air Flow/Pressure Sensor Circuit Range/Performance Bank 1
- DTC P2432: Secondary Air System Air Flow/Pressure Sensor Circuit Low Bank 1
- DTC P2433: Secondary Air System Air Flow/Pressure Sensor Circuit High Bank 1
- DTC P2440: Secondary Air System Switching Valve Stuck Open Bank 1
- DTC P2441: Secondary Air System Switching Valve Stuck Closed Bank 1
- DTC P2442: Secondary Air System Switching Valve Stuck Open Bank 2
- DTC P2443: Secondary Air System Switching Valve Stuck Closed Bank 2
- DTC P2444: Secondary Air System Pump Stuck On Bank 1
- DTC P2530: Ignition Switch Run Position Circuit
- DTC P2610: ECM/Pcm Engine Off Timer Performance
- DTC U0073: Control Module Communication Bus Off
- DTC U0101: Lost Communication With TCM
- DTC U0122: Lost Communication With Vehicle Dynamics Control Module
- DTC U0155: Lost Communication With Instrument Panel Cluster (IPC) Control Module
- DTC U0402: Invalid Data Received From TCM
- DTC U0416: Invalid Data Received From Vehicle Dynamics Control Module
- DTC U0423: Invalid Data Received From Instrument Panel Cluster Control Module
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.
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