2001 Ford Ranger4.0L SOHL Check engine light came on and code reads P0171 left bank lean and R0174 right bank lean. What are the possible causes of this and how can I fix this?

. Could be the upper and or lower intake manifold gaskets leaking. Find out the torque sequence and the amount of torque and try tightening. Perform when engine is cold.

. In some cases, simply cleaning the MAF sensor does the trick. Consult your service manual for its location. Take it off and spray with electronics cleaner or brake cleaner. Be careful not to damage the MAF sensor and make sure it's dry before reinstalling.

. Inspect all vacuum and PCV hoses--replace if necessary.

. Check for a dirty fuel filter and proper fuel pressure .

Afterwards, reset the computer and see if this solved the problem.

It is more than likely your oxygen sensors not working properly . Which is telling the engine to run less fuel and more air.

How many and where are the sensors located?