PAIR OF PREMIUM POST CATALYTIC OXYGEN O2 SENSORS FOR HOLDEN CALAIS VE VF L77 6.0L V8Premium post cat O2 sensors are manufactured utilizing proven OE technology and are guaranteed to provide durable and efficient performance. The Post catalytic oxygen sensor is located after the catalytic converter and monitors its efficiency by comparing the exhaust that flows into the and out of the converter. This sensor ensures the lowest possible output of environmentally harmful engine emissions. These post cat oxygen sensors suit Holden