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Q: Check engine light on & OBD #P0171

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For three months, the Check Engine Light has been coming on and off. The Onboard Diagnostic #P0171 showed when I went in to have a checkup. The following have been replaced: gas cap, mass air-flow sensor, and spark plugs. The told me that it was the mass air-flow sensor because the system is running too lean. The check engine light still comes on every 2-3 weeks. I feel like I’m having the wrong things fixed. Please give me your professional advice on this problem.

P0171 for your car is "system too lean." The most common cause is a vacuum leak and it can come from a leaky hose or a leaky gasket. However, I did a quick search and found someone on the forums with your exact car and exact problem and his issue was a leaky fuel injector seal. You may want to try that first since those are cheap. Alternatively, a qualified professional from YourMechanic can come to your car’s location to inspect the Check Engine Light firsthand to have this corrected appropriately.

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