2007 Subaru Forester
Mileage
173,333
Service Date
11/19/2025
Services Performed
- (continued from above) below threshold bank 1. Check and advise Diagnostic Steps; Step 1. Started the vehicle and verified the check engine light is on. Step 2. Scanned vehicle for diagnostic trouble codes. Verified trouble code P0420 (catalyst efficiency below threshold bank 1). Step 3. Checked for technical service bulletins. There are no bulletins for P0420 on this vehicle. Step 4. Performed diagnostic test per manufactures procedures as follows: Step 5. Checked exhaust system for leaks. There are no leaks currently present in the exhaust system. Step 6. Checked waveform data of air fuel lambda and rear oxygen sensor using a scan tool. Verified the rear oxygen sensor is switching excessively indicating a failed catalyst. Step 7. Checked air fuel sensor and oxygen sensor operation. Both sensors are operating as designed. Step 8. Checked fuel control system. Fuel control system is between +-10% (good). Correction – Recommend replacement of catalytic converter assembly and retest.
Frank S. gave our service a 5 star review on 11/19/2025
