Ford P0171-System Too Lean Bank 1

Ford P0171 System Too Lean Bank 1

Code P0171 Ford is DTC code stored in ECM(engine control module)when it detect lean condition in the fuel system Bank 1. This condition occurs when there is too much air and insufficient amount of fuel in the air/fuel mixture. Engine control module (ECM) monitor air/fuel mixture ratio using sensor and adjust it duly. When ECM detect a lean condition it illuminates the engine check light and trigger p0171.

Fault Location- Fuel System Bank 1

Possible Causes Code P0171 Ford

1.Vacuum leak allowing outside air to enter engine causing air/fuel mixture to become too lean.

2.ECM receiving incorrect information about the amount of air entering engine due to malfunctioning MAF sensor (Mass Air Flow Sensor)

3.Choke fuel injector reducing the amount of fuel being delivered to engine, causing lean condition.

4.Failing or weak fuel pump resulting in reduced fuel pressure, causing lean condition.

5.Clogged or dirty throttle body can cause the throttle plate to stick to its body resulting engine running lean.

6.Exhaust leak before HO2S sensor can create vacuum causing engine running lean.

7.Damaged or weak intake manifold gasket can cause vacuum leak resulting lean condition.

Ford P0171 DTC Code Possible Symptoms

Reduced engine performance, decreased fuel efficiency in the vehicle, engine misfire or may experience rough idling, engine may stop running at idling or while driving especially under heavy load, increased emissions resulting fail emission test, engine check light illuminates.

How To Fix Code P0171 Ford

1.Locate and repair vacuum leak using silicon adhesive or specialized vacuum leak repair product.

2.Replace MAF sensor(mass air flow sensor) to restore proper functioning of engine.

3.Clean fuel injector with specialized cleaning equipment or replace with new injector if cleaning does not fix the issue.

4.Clean throttle body using throttle body cleaner or replace with new one if cleaning does not fix the issue.

5.Repair and seal leaks in exhaust system.

6.Replace weak or damaged intake manifold gasket to restore proper functioning.


Its important to have the vehicle inspected and diagnosed by professional mechanic to find and resolve issue related with code p0171 ford for proper repair.

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