Abstract: The present invention relates to an exhaust system having a riser adapted to be mounted to the exhaust inlet of a marine engine and a turndown connected to the riser. The riser and turndown define a primary exhaust passage to direct exhaust gases downwardly toward the discharge opening. A secondary passage, a tube, is integrated to the turndown within the primary exhaust passage. An O2 sensor is mounted within the tube. The tube has a diameter that is less than the diameter of the primary exhaust passage. With the diameter being less, the exhaust gases in the secondary passage have a pressure that is greater than in the primary exhaust passage which eliminates or at least reduces the ability for water to enter the secondary passage protecting the O2 sensor from damage.

Abstract: The present invention relates to an exhaust system having a riser adapted to be mounted to the exhaust inlet of a marine engine and a turndown connected to the riser. The riser and turndown define a primary exhaust passage to direct exhaust gases downwardly toward the discharge opening. A secondary passage, a tube, is integrated to the turndown within the primary exhaust passage. An O2 sensor is mounted within the tube. The tube has a diameter that is less than the diameter of the primary exhaust passage. With the diameter being less, the exhaust gases in the secondary passage have a pressure that is greater than in the primary exhaust passage which eliminates or at least reduces the ability for water to enter the secondary passage protecting the O2 sensor from damage.