I have the same engine as yours, D16Y7, unless you have a different engine. The Catalytic Converter/Exhaust Manifold are one. There should be a cover (heat shield?) at the top of the Catalytic Converter. There are two Oxygen Sensors. Each Oxygen Sensors have four wires connected to it. The first one is located before the Catalytic Converter (integrated into the Exhaust Manifold). The only way to remove that is to remove the "top cover" first.The second one is located after the Catalytic Converter. The landmark will be the opposite of the radiator (air conditioning condenser), underneath the Catalytic Converter, before the small pipe. You need the ramp, or jack the car up, in order to see it. You need to remove the engine splash shield (the black thing underneath), in order to have room for removal.Heated Oxygen Sensor (USA) = Lambda Sensor (UK)