We have a 2004 Ford Freestar with lean codes P0171 & P0174. The car ran horrid until the gaskets and actuator rods were fixed. Now it drives great but these codes will not go away.


What we have done so far:
-Replaced MAF Sensor
-Replaced manifold gaskets
-Replaced all 4 O2 sensors
-Fixed the IMRC actuator rod
-Replaced the hose
-Replaced PCV valve


Any ideas?

 

If the tool you are using cannot clear the codes, if the problem is fixed,the codes will clear by themselves.

If, however, you clear them and they keep coming back, there is a problem that is affecting both banks.

You might look for air getting into the intake between the MAF and the throttle body.
If the air is not accounted for the PCM will only allow so much fuel to be injected based on what the MAF sees.