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. Precautions While Driving
In Rain Avoid driving in deep water and on flooded roads. This can damage the engine or driveline, or cause electrical component failure. Other Precautions If there is a strong impact with something under the vehicle, stop in a safe location. Check the underside of the vehicle for damage ...