Where is the oil filter located on a 2003 Pontiac Sunfire?

It is directly in front of where you add oil, you will need a 24 mm socket with an extension to reach the black top enclosure. If you have a Ecotech engine it's located on the front of the block, drivers side. It is not a canister-sytle oil filter. These engines have a cartridge-type oil filter (real easy to change). You should see a black plastic cap with a large hex nut on top. Unscrew this cap and the filter will come out with the cap. Have some paper towels ready as a small amount of oil is still captured around the filter and will drip out as you remove the filter. My daughter's 2003 Pontiac Sunfire with a 2.2 liter Ecotec 4 cylinder required a 32mm socket, not a 24mm, to unscrew the black cap. Perhaps GM changed oil filter caps during the production run. The rest of the above answers is correct. On the cap it reads "25Nm" with an arrow indicating to tighten clockwise. If you use a torque wrench to tighten the black cap, 25 Newton Meters is just right. 25 Newton Meters is the same as 18.5 ft-lbs torque. I didn't use a torque wrench but just tightened it approximately the same as a regular screw on oil filter. Good luck. Yes, my 2003 also needed a 32mm socket (which I had to order online as I couldn't find it anywhere else. Too big). So I guess they upped the size at some time. Phil

After changing the oil on probably at least 200 Ecotechs I have yet to see one that is not 32 mm, also it is important to replace the o-ring every time you replace the filter, and do not over-tighten, as you can crack the oil filter cap.