Hello, I have a 1999 civic lx and a P0171 code keeps popping out, my mechanic has cleaned every sensor, throttle, replaced fuel filters/spar plugs and wirings, also replaced O2 sensors. I still smell gas though the A/C and the code is still popping up.

What can i do now?

 

Check for an exhaust leak near or upstream of the primary O2 sensor - cracked exhaust manifold or leaking exhaust gasket.