Recently the SES light came on in my 03 galant 4cyl and I used a buddy's obdII to read the code (which has came on twice now).

Code read p0135 and in the generic code definitions in the book the obdII had was "Oxygen O2 Sensor Heater Circuit Malfunction (bank 1, sensor 1).

The mitsu dealership wants to charge me 140 + 75 for what they think is a replacement o2 sensor.

My question is can I just buy a sensor from advanced auto parts for like 80 bucks then do the change myself, if in fact it is the o2 sensor itself that needs replaced. and how would I go about changing the sensor, is there an instruction manual somewhere? Thanks in Advance.

-Matt