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DTC - Diagnostic Trouble Codes information

P0171

Powertrain Codes

P0171 - System Too Lean Bank 1

Symptoms

- Engine Light ON (or Service Engine Soon Warning Light) - Excessive Fuel Consumption

Possible Causes

- Intake air leaks - Faulty front heated oxygen sensor - Ignition misfiring - Faulty fuel injectors - Exhaust gas leaks - Incorrect fuel pressure - Lack of fuel - Faulty Mass Air Flow (MAF) sensor - Incorrect Positive Crankcase Ventilation (PCV) hose connection

When Detected

- Fuel injection system does not operate properly. - The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)

Tech Notes

Dirty air filter of faulty air flow sensor are common causes for the P0171 code of the problem.

Description

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios. In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).

Information For Specific Makes

P0171 1999 FORD WINDSTAR P0171 2000 FORD WINDSTAR P0171 2001 FORD WINDSTAR P0171 2002 FORD WINDSTAR P0171 2003 FORD WINDSTAR P0171 FORD P0171 HONDA P0171 INFINITI P0171 KIA P0171 MAZDA P0171 MITSUBISHI P0171 NISSAN P0171 SUBARU P0171 TOYOTA P0171 VOLKSWAGEN P0171 ACURA P0171 BMW P0171 CHRYSLER P0171 DODGE P0171 JEEP P0171 HYUNDAI P0171 ISUZU P0171 LEXUS P0171 SCION P0171 AUDI P0171 JAGUAR