^ Classic symptom is rough (slipping) 1-2 shift when warm. Possibly a funky speedo, flashing green od off light and other erratic shift points. I've never had a trouble code. Your 99 dohc has the 19 pan bolt ax4n tranny. Vss is almost a maintenance item on a 99tec (dohc). I've had to change 5-6 over the years. Yes, you can access from the top pass. side. It's located directly behind the black plastic egr solenoid (evr) way down atop the tranny under an open-ended foil heat shield. All work performed blindly and by feel. Locate and pull up heat shield and unplug vss. Next, with a 1/4" dr. ratchet, 2 long exts. (preferrably wobble) and a 10mm socket all taped together, remove hold down bolt. Pull vss from tranny. Installation is reverse of removal. Part costs ~$20-25. Cjinohio03, might read the thread on here today: "transmission hard shift when stopping at 5 mph" by alwaysthinking.