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 BaseFACTORY OEM SERVICE PROCEDURE
Drive Cycle A
| DTC | Item | Condition |
|---|---|---|
| P0030 | A/F/O2 HEATER CONTROL CIRCUIT BANK 1 SENSOR 1 | - |
| P0087 | FUEL RAIL/SYSTEM PRESSURE - TOO LOW BANK 1 | Complete diagnosis with drive cycle B as well. |
| P0088 | FUEL RAIL/SYSTEM PRESSURE - TOO HIGH BANK 1 | Complete diagnosis with drive cycle B as well. |
| P0128 | COOLANT THERMOSTAT (ENGINE COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE) | - |
| P013A | O2 SENSOR SLOW RESPONSE - RICH TO LEAN BANK 1 SENSOR 2 | - |
| P013B | O2 SENSOR SLOW RESPONSE - LEAN TO RICH BANK 1 SENSOR 2 | - |
| P0141 | O2 SENSOR HEATER CIRCUIT BANK 1 SENSOR 2 | - |
| P014C | A/F/O2 SENSOR SLOW RESPONSE - RICH TO LEAN BANK 1 SENSOR 1 | - |
| P014D | A/F/O2 SENSOR SLOW RESPONSE - LEAN TO RICH BANK 1 SENSOR 1 | - |
| P015A | A/F/O2 SENSOR DELAYED RESPONSE - RICH TO LEAN BANK 1 SENSOR 1 | - |
| P015B | A/F/O2 SENSOR DELAYED RESPONSE - LEAN TO RICH BANK 1 SENSOR 1 | - |
| P0171 | SYSTEM TOO LEAN BANK 1 | Complete diagnosis with drive cycle B as well. |
| P0172 | SYSTEM TOO RICH BANK 1 | Complete diagnosis with drive cycle B as well. |
| P0244 | TURBOCHARGER/SUPERCHARGER WASTEGATE SOLENOID "A" RANGE/PERFORMANCE | - |
| P0300 | RANDOM/MULTIPLE CYLINDER MISFIRE DETECTED | Complete diagnosis with drive cycle B as well. |
| P0301 | CYLINDER 1 MISFIRE DETECTED | Complete diagnosis with drive cycle B as well. |
| P0302 | CYLINDER 2 MISFIRE DETECTED | Complete diagnosis with drive cycle B as well. |
| P0303 | CYLINDER 3 MISFIRE DETECTED | Complete diagnosis with drive cycle B as well. |
| P0304 | CYLINDER 4 MISFIRE DETECTED | Complete diagnosis with drive cycle B as well. |
| P0420 | CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD BANK 1 | - |
| P0459 | EVAP SYSTEM (CPC) PURGE CONTROL VALVE "A" CIRCUIT HIGH | - |
| P1191 | FUEL RAIL PRESSURE SENSOR "A" CIRCUIT NO ACTIVITY DETECTED | Complete diagnosis with drive cycle B as well. |
| P2096 | POST CATALYST FUEL TRIM SYSTEM TOO LEAN BANK 1 | Complete diagnosis with drive cycle B as well. |
| P2097 | POST CATALYST FUEL TRIM SYSTEM TOO RICH BANK 1 | Complete diagnosis with drive cycle B as well. |
| P2195 | A/F/O2 SENSOR SIGNAL BIASED/STUCK LEAN BANK 1 SENSOR 1 | - |
| P2196 | A/F/O2 SENSOR SIGNAL BIASED/STUCK RICH BANK 1 SENSOR 1 | - |
| P2270 | O2 SENSOR SIGNAL BIASED/STUCK LEAN BANK 1 SENSOR 2 | - |
| P2271 | O2 SENSOR SIGNAL BIASED/STUCK RICH BANK 1 SENSOR 2 | - |
Diagnostic procedure:
- Drive for 20 minutes or more at a constant speed of 80 km/h (50 MPH) or more.
- Stop the vehicle and idle for one minute.
- Read the temporary code using the Subaru Select Monitor or general scan tool. Ref. to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>Read Diagnostic Trouble Code (DTC)>OPERATION .
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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