Service bulletins for the 2015 Subaru WRX
A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.
446 on file from NHTSA, as of 2026-10-19.
About P0420 on the 2015 Subaru WRX: what the code means, and the bulletins and recalls about the same components.
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By trouble code
Only bulletins with trouble code: P0420 are shown. Show all
| 09-131-25R | 2025-09-02. Service bulletin. ELECTRICAL SYSTEM; ENGINE. This bulletin announces the diagnostic procedures and availability of reprograming files to rectify the following Diagnostic Trouble Codes (DTCs). • P2404: EVAP System Leak Detection Pump Sense Circuit Range/Performance. • P0420: Catalyst System Efficiency Below Threshold Bank 1. (not applicable for 15-18 models) |
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| 09-131-25 | 2025-05-01. Service bulletin. ENGINE; ELECTRICAL SYSTEM. This bulletin announces the diagnostic procedures and availability of reprograming files to rectify the following Diagnostic Trouble Codes (DTCs). The ELCM may accumulate condensation causing the inaccurate detection of P2404. P0420 may become falsely detected due to unstable combustion caused by a downshift. The new reprogramming files contains enhanced software allowing for condensation conditions and downshift rotational speeds be more accurately detected by the Engine Control Module (ECM). |
| 09-131-25 | 2025-04-01. Service bulletin. ENGINE; ELECTRICAL SYSTEM. "This bulletin announces the diagnostic procedures and availability of reprograming files to rectify the following Diagnostic Trouble Codes (DTCs). • P2404: EVAP System Leak Detection Pump Sense Circuit Range/Performance. • P0420: Catalyst System Efficiency Below Threshold Bank 1. (not applicable for 15-18 models)" |
The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.