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Toyota Repair/Corolla check engine light


I have a 2005 Corolla with 150,000 miles on it.  The check engine light is on steady, so I put a code reader and it is P0171 - fuel injection system lean.  But that's as far as any book goes with it.  Which component could be malfunctioning?

The lean condition may be caused by a vacuum leak at any of the vacuum switching valves or a vacuum hose connected to the air filter or other components visually inspect the hoses, after that the most common failure is bad mass airflow sensor, it's located on top of the intake hose assembly between the throttle body and close to the air filter, it has an electrical connector with a few wires on and two phillips screws, replace this sensor.  

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Ted Ritter


I have more than 28 years experience as toyota technician, I will be able to answer most questions related to the Toyota product line up to the present year models,I am located in the US but welcome questions from other regions of the world. When asking a question please provide specific information: year,model, engine,transmission information. Provide as much information as possible including a brief repair history if possible. I have been a volunteer here for more ten years an have answered over 16,000 questions helping Toyota owners with their problems and save thousands of dollars without any compensation, some of my answers are published on many other websites including google and various automotive forums. DONATIONS ARE VERY MUCH APPRECIATED, IF YOU HAVE RECIEVED HELPFUL INFORMATION PLEASE MAKE A DONATION. AS OF TODAY (JULY 22, 2014) ALL REQUESTED GRAPHICS, ILLUSTRATIONS, DIAGRAMS, PHOTOS, WILL REQUIRE THE MINUMUM DONATION UP FRONT.


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