cel code i think it means o2 sensor

[brenin]

1st off i dont notice a difference in the performance maybe mpg's are alot worse.. anyways the code i pulled is H02S heater control circuit low (bank 1 sensor 1) that is what it said i to know were it is on the car or is there two of um..??i almost forgot 04 wrx

[silverautorex]

yeah that's the front o2 sensor right near the uppipe. unfortunately that is the most important o2 sensor. mine went last month on my 02 wrx. the first few days u won't really notice anything different, but after that perfomance will decrease and it will fell like the car bogs down during acceleration.

[EvoEatr]

+1..your fuel mileage might also be affected..

[CJ05]

That's a beeyotch to get to also. Real PITA especially having to deal with that heat shield for the headers.

[brenin]

thanx for all the help guys im new to the site and i love it so far....