Honda Civic Service Manual: Engine Cooling

Engine

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Coolant Replacement (R18A9)

1. Radiator Cap 1. Wait until the engine is cool, then carefully remove the radiator cap. ...

See also:

Honda Civic Owners Manual. If the Low Oil Pressure Indicator Comes On
Reasons for the indicator to come on Comes on when the engine oil pressure is low.  What to do as soon as the indicator comes on  Immediately park the vehicle on level ground in a safe place.  If necessary, turn the hazard warning lights on.  What to do after parking ...