Honda Civic Service Manual: Battery System

Electrical

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Battery Removal and Installation

Removal 1. Battery Terminal - Disconnection 1. Make sure the ignition switch is in LOCK (0). ...

See also:

Honda Civic Service Manual. Cylinder Head Inspection for Warpage (R18A9)
1. Fuel Pressure - Relieving (Between the engine and the manual shut-off valve) (Natural Gas Model) Compressed natural gas is flammable and highly explosive. You could be killed or seriously injured if leaking natural gas is ignited. ...