I have a 2001 Ford Taurus V6. Engine light on. There are 2 codes-PO172 & PO175

you have o2 sensor circuit issues. there is a fuel trim problem,seek diag and est as this could be several issues

Hi Bob. I had the same problem with my Taurus. I didn't have the codes checked so I don't know what yours mean but I replaced the spark plugs which is always a good one to start with expense wise. My idling actually got worse. I also thought I had no vacuum leaks but I heard an unusual hissing after changing the plugs. The 90 degree boot on the air intake to the pcv valve was split around the 90. I replaced the boot and pcv valve which can also cause rough idle. Problem solved. also if you have a slight miss or hesitation around 1500 rpms. I would suggest a new ignition coil and plug wires I just changed mine and what a difference it made. You can replace all of this for under 200 dollars through advance auto parts. Hope this helps Dustin,