Bosch Post-Catalyst Oxygen Sensor

The Bosch Post-Catalyst Oxygen Sensor (downstream O2 sensor) monitors the oxygen content of the exhaust gas after the catalytic converter. It sends this signal to the engine control unit, which uses it to check catalytic converter efficiency and support emissions control. Bosch also sells these sensors as lambda sensors.

Key Features:

• Sits downstream of the catalytic converter to monitor converter performance
• Helps the engine control unit keep emissions systems working correctly
• Supports fuel efficiency and smooth engine operation
• Made by Bosch, which invented the automotive oxygen sensor and supplies many vehicle manufacturers
• Sensor designs vary by application, and each variant is listed under its own part number

A failing downstream oxygen sensor can trigger the check engine light and cause emissions test failures. Replacing it with a quality Bosch sensor helps restore proper exhaust monitoring and engine management.