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Q: Car runs lean, check engine light on

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Lately, my car started to run lean. I've had several repairs done on it. I changed the spark plugs, the fuel filter along with the fuel injector number one. The manifold has been replaced as well. Also, I changed the MAP sensor purge valve. Despite all the repairs, the check engine light is illuminated again and the problem persists. What do you suggest I should do next?

Hello. Thanks for writing in about your 2009 Audi A5 Quattro. If you are having a lean condition, then the fuel pressure needs to be checked. The most common cause of a lean code on this car is either low fuel pressure from a failing fuel pump or a bad air flow sensor. Both need to be tested to see which one is causing this. If you want to have this done, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose the Check Engine Light and come up with the appropriate repairs.

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