Truck threw a code

[dboat]

My brothers 2003 4.6L Ford pickup threw a code that read system too lean, bank 1... what next? he has asked for some help.

Thanks
Dana

[Sixpipes]

My brothers 2003 4.6L Ford pickup threw a code that read system too lean, bank 1... what next? he has asked for some help.

Thanks
Dana

Check all the hose connections on the passenger's side from the supercharger to the valve cover. Also, any other loose connections that might be pulling air into the intake behind the MAF (under boost). That's a pretty common code. Had it on my truck a number of different times. :cool:

[Sixpipes]

Ummmm...OK, forget what I said. No supercharger, but probably still a loose hose somewhere (vacuum or otherwise).

[PUMP]

P0171 Code possible causes from the Service CD fro 2003 4.6L engine

Air Measurement System

MAF sensor (contaminated, damaged, malfunctioning, etc.)
Fuel System

Fuel pressure regulator (leaking, malfunctioning, etc.).
Fuel filter plugged, dirty.
Fuel pump (weak, check valve leaking, etc.).
Leaking/contaminated fuel injectors.
Low fuel pressure or running out of fuel.
EVAP canister purge valve leaking (when canister is "clean").
Fuel supply line restricted.
Fuel rail pressure sensor (incorrect reading).
Air Induction System

Air leaks after the MAF.
Vacuum Leaks.
PCV system (leak, valve stuck open, etc.)
Improperly seated engine oil dipstick.
Exhaust System

Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.)..
EGR System

EGR valve tube/gasket leak
EVR solenoid vacuum leak
Secondary Air Injection

Damaged/malfunctioning secondary air injection system (mechanically stuck valve).

[dboat]

Thanks guys, I am sure he will appreciate it.. I know I do

Dana