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 MANUALSHONDA2020CIVIC SI, 4D SEDANREPAIR AND DIAGNOSIS (SINGLE PAGE)QUICK LOOKUPSDTC INDEXIMMOBILIZER-KEYLESS CONTROL DTCSIMMOBILIZER-KEYLESS CONTROL UNIT

2020 Honda Civic Si, 4D Sedan

Immobilizer-Keyless Control Unit

2020 Honda Civic Si, 4D SedanSECTION Immobilizer-Keyless Control Unit

DTC	Description	DTC type
U1280	B-CAN communication bus line error (BUS-OFF)	Loss of communication
U1281	Lost communication with MICU (body control module) (MICU frame)	Loss of communication
U128D	Lost communication with METER	Loss of communication

RENDER: 1.0x

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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.