Description

Oxygen (Lambda) Sensor for the rear, post-catalyst position in the exhaust system.

Mounted in the downpipe downstream of the catalytic converter, this sensor monitors the oxygen content of the gas leaving the catalyst. The engine management ECU compares its signal against the pre-catalyst sensor to assess catalyst conversion efficiency and to apply long-term trim correction to closed-loop fuelling. Unlike the pre-catalyst sensor it does not control fuelling directly, so a failed unit generally presents as a catalyst efficiency or sensor circuit fault code rather than as a driveability complaint.

Apply anti-seize compound to the sensor thread only when fitting, and keep the sensor tip free of grease and other contamination.