P0171 2006 Ford F150 -

Question

in freeze frame on my obd II reader says c l fault

Answer 1

P0171 Fuel trim lean Bank 1

Lean fuel trim on one side of the Bank check for vacuum leaks especialy at Bank 1. Bank 1 is where cylinder 1 is located at, what you look for are vacuum leaks and this includes sparkplugs. When the scan too data has  CL Fault what the ECM uses for this is actvity from the 02 sensor, The engine coolant temperature may be in closed loop, but CL fault is where the ECM cannot make fuel trim adjustment based on the 02 sensor. Correct for the lean code condition this would fix the CL fault