Poor mileage, codes P1529, P0722
 

Hi all, bought a 2001 Accent for my daughter, I am only getting 25mpg, I took the car to autozone today and they gave me codes P1529 and P0722, Auto crankshaft position sensor and Speed sensor ??? anyway,while driving tonight i noticed the following, shift smooth , peppy , no bogging at all. While watching the tach at about 40 mph it was at about 600 rpms, when on the interstate at 70 to 75, tach read about 3300. While at the 40 mph range i noticed the tach would once in awhile drop right down to 0 and back up, hang around 2000 or 650 range intermittently. I put on the 1st pipe new, new filter and fluid in trans, all new brakes drums and rotors, new oil, new plugs, I dont want to go throwing too much money into this before i get your opinoins. I also read I should get the trans reprogrammed, flashed after i replace any parts or ??
Thanks to any and all advise that will help me out. 1.6 engine 2001

A faulty crankshaft position sensor would account for all your issues. Replace it...