help me

[Erti]

Hello
2010 Mustang 4.6 3v , from cold idling no problem, when the fan turns on the fuel trim will be high. i get p0171 p0174.

 

[07 Boss]

That actually means your fuel trim is low and your running lean. The fan coming on should have nothing to do with it. I don't think the codes are caused by an exhaust leak because it's on both sides which means for some reason you're not getting enough fuel.

 

[Dino Dino Bambino]

Those are lean codes, and the fuel trim is high as the ECU is trying to correct it.
If this only happens when the fan comes on, the only thing I can think of is the intake pipe isn't properly attached to the throttle body and some of the fan wash is leaking into the intake tract.

 

[Erti]

 

[Erti]

 

[Erti]

192.2F on fan= high fuel trim, 0F-192.2F= correct fuel trim