Service bulletins for the 2021 Subaru Forester
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.
371 on file from NHTSA, as of 2026-10-19.
About P0420 on the 2021 Subaru Forester: what the code means, and the bulletins and recalls about the same components.
By type
By component
By trouble code
Only bulletins with trouble code: P0420 are shown. Show all
| 09-110-23R | 2023-12-05. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING. This Service Information Bulletin announces diagnostic service procedures to be followed when DTC P0420 (Catalyst System Efficiency Below Threshold Bank 1) is detected by the Engine Control Module (ECM). |
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| 09-110-23 | 2023-11-06. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL:CATALYTIC CONVERTOR. This Service Information Bulletin announces diagnostic service procedures to be followed when DTC P0420 (Catalyst System Efficiency Below Threshold Bank 1) is detected by the Engine Control Module (ECM). If DTC P0420 is found to be stored in the ECM, follow the diagnostic procedures outlined below. |
The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.