The specifications of vent holes on the protective thimble on heated oxygen sensor (device that detects the amount of oxygen in the exhaust stream and sends that information to the electronic control module in the gaseous emissions control equipment) are improper. Because of this, at the time of engine start, moisture in the exhaust at a cold temperature may come in contact with the oxygen sensor element, causing the heated element cooled and contracted rapidly. This can result in breakage and malfunction of the sensor, and the exhaust level may exceed the requirement.