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

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.

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