check engine light

code P0171 and PO174 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters (K&N, etc.) can cause the MAF to become dirty if the filter is over-oiled
There could be a vacuum leak downstream of the MAF sensor.
Possible solutions include:

In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are 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

[quote:cbd4a58aa7="timl"]i have a 1996 explorer with 170,000 miles .the check engine light comes on.the code says it has lean condition in both right and left banks.is this oxygen sensors.[/quote:cbd4a58aa7]thanks peppermjr your solution seems to have done the trick.very appreciated