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.
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HOMESERVICE MANUALSSUBARU2016LEGACY 2.5IREPAIR AND DIAGNOSISBODY & FRAMEDOOR LOCKSSECURITY AND LOCKS - KEYLESS ACCESS (W/PUSH BUTTON START) (DIAGNOSTICS)DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)DTC B278D ID CODE BOX JUDGMENT CIRCUITDTC DETECTING CONDITION
2016 Subaru Legacy 2.5i
DTC B278D Id Code Box Judgment Circuit: DTC Detecting Condition
2016 Subaru Legacy 2.5iSECTION DTC Detecting Condition
When the evaluation of the ID code box setting circuit via the hard wire is judged as none, ID code box communication is received. (at new registration)
RENDER: 1.0x
NO RELATED
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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.