# Service bulletin 09\-131\-25

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.

- Type: Service bulletin
- NHTSA id: 11017434
- Published by NHTSA: 2025\-05\-01
- Manufacturer's number: 09\-131\-25
- Manufacturer's date: 2025\-04\-08
- NHTSA component: ENGINE; ELECTRICAL SYSTEM

## NHTSA's summary

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 \(ECM\).

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2025/MC-11017434-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2025/MC-11017434-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Electrical system, Engine

## Trouble codes named

P0420, P2404

## Vehicles listed

- 2015 to 2021 SUBARU WRX STI

## Recalls for the same vehicles and component

- [17V625000](/recalls/nhtsa/17V625000.md), 2017-10-06: ELECTRICAL SYSTEM:WIRING
- [16V162000](/recalls/nhtsa/16V162000.md), 2016-03-21: ENGINE AND ENGINE COOLING:ENGINE:GASOLINE:TURBO/SUPERCHARGER

## Other bulletins for the same vehicles and component

- [SubaruNet Announcement \(M](/bulletins/11037943.md), 2026-10-05, Other: ELECTRICAL SYSTEM; UNKNOWN OR OTHER. This announcement provides information on a new software update for the Midtronics Dss and DCA machines.
- [18\-244\-26](/bulletins/11037938.md), 2026-10-05, Service bulletin: ELECTRICAL SYSTEM. "This Bulletin announces additional troubleshooting steps for the following DTCs: DTC C1956: RH Actuator Circuit DTC C1957: LH Actuator Circuit"
- [15\-333\-25R](/bulletins/11037929.md), 2026-10-05, Service bulletin: UNKNOWN OR OTHER; ELECTRICAL SYSTEM. This bulletin contains illustrations of exchange components and their manufacturer as well as a description of the proper exchange procedure. This is an revised version of the original bulletin.
- [15\-322\-25R](/bulletins/11037928.md), 2026-10-05, Service bulletin: ELECTRICAL SYSTEM; UNKNOWN OR OTHER. In the interest of customer satisfaction, Subaru of America, Inc. \(SOA\) is extending the New Car Limited Warranty coverage for the CP1 \& Gen 3.1 Head Unit used in the listed models and model years to \(8\) eight years / 150,000 miles to cover certain qualifying repairs to the infotainment audio system. This is an revised version of the original bulletin.
- [15\-304\-22R](/bulletins/11037927.md), 2026-10-05, Service bulletin: ELECTRICAL SYSTEM. This bulletin has been developed to outline the steps for gathering basic but essential information during diagnosis of Infotainment concerns. This is an revised version of the original bulletin.
- [15\-308\-23R](/bulletins/11036807.md), 2026-09-03, Service bulletin: ELECTRICAL SYSTEM. This Service Information Bulletin outlines a systematic procedure for diagnosing parasitic draw \(dark/standby current\) in vehicles experiencing battery drain when the ignition is off, leading to no\-start conditions or frequent jump\-starts.This is an revised version of the original bulletin.
- [15\-304\-22R](/bulletins/11036796.md), 2026-09-03, Service bulletin: ELECTRICAL SYSTEM. This Bulletin has been developed to outline the steps for gathering basic but essential information during diagnosis of Infotainment concerns. \(This is an revised version of the original bulletin.\)
- [Article Locator](/bulletins/11036794.md), 2026-09-03, Other: ELECTRICAL SYSTEM. Techtips newsletter locator index.
- [15\-333\-25R](/bulletins/11036789.md), 2026-09-03, Service bulletin: ELECTRICAL SYSTEM. This bulletin contains illustrations of exchange components and their manufacturer as well as a description of the proper exchange procedure. This is an revised version of the original bulletin
- [02\-193\-24R](/bulletins/11034269.md), 2026-07-02, Service bulletin: ENGINE. This bulletin provides updated parts information and a service procedure to follow for removing accumulated carbon deposits from fuel injectors and internal engine components \(e.g. intake valves and / or manifold, and combustion chambers\). \(This is an revised version of the original bulletin.\)

JSON: [/v1/bulletins/11017434](/v1/bulletins/11017434)

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