Subaru Repair: 99 outback sport O2 sensor, Subaru check engine light

Question
My son has a 99 outback sport.  The check engine light came on and he took it to a shop who hooked it up and said he needs a oxygen/heat sensor and the part cost is over 200 bucks.  I have checked online and cannot fine an oxygen/heat sensor but pleny of oxygen sensors for before and after the cat. converter.What are they talking about?

Answer
The O2 sensor can also go by the name H2OS.

Which means Heated O2 sensor.

O2 sensors have to reach a certain temperature before they work.  Rather than wait for the engine exhaust to heat up the 02 sensor manufacturer started heating the o2 sensors quite a few years ago to help improve fuel economy and add more precise fuel management while the engine was warming up.  Rather than wait until the Exhaust heats up the O2 sensor to go into what is called closed loop.

Hope that helps

Justin

http://allwheeldriveauto.com/