2000 Millenia has P0173 & p1173 codes. Located a broken t connector for the vacume lines and replaced but I think the o2 Front LH sensor may also need to be replaced. Problem is I can not trace where the O2 Sensor plug is located. It looks like the wire goes from the exhaust connection up and through a space in the engine but can not find this (four wire) connection on the rear of the engine. I was able to trace and located the connection for the upstream 02 sensor and I thought the front sensor would plug in around the same area, but no luck. Can anyone tell me where the plug goes? Thanks, Bill

 

if this is a 2.3, there is an air duct that goes to the rear ic. the front of the air duct bolts to a large plastic part of the intake, the boot from the mas is connected to this large plastic part of the intake. you take off that large plastic part, and you will see the connection