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Discussion Starter · #1 · (Edited)
Hey, my mothers car has check engine light on, I scanned the car and got P0171, which is;
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:
Fuel system
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Induction system:
Air leaks after the MAF.
Vacuum Leaks.
PCV system.
Improperly seated engine oil dipstick.
EGR system:
Leaking gasket.
Stuck EGR valve.
Leaking diaphragm or EVR.
Base Engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
A SHRTFT-1,2 PID value between -25% to +35% and a LONGFT-1,2 PID value between -35% to +35% is acceptable. Reading beyond these values indicate a failure.

Anyone know more specifically what it could be ?


Edit-BTW it's an 2005 ZXW

1,036 Posts
Clean the mass air flow meter and clear the codes. Dirty MAF can cause lean codes. Very common on ford products

7,946 Posts

also, a bad o2 will cause this code.

best way to clean the MAF is use CRC Maf cleaner from your local parts store. remember not to touch any of the wires on the inside of the unit.
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