Q: Error codes, engine light on

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I took the car to the shop and after reading the codes, the car got two error codes. These were: P0140, indicating that the O2 sensor circuit has no activity, Bank 1, and P0171, indicating that the system is too lean, Bank 1. Also, the dashboard shows the engine light on. What does this mean and what should I check and fix?

Hello there. When these codes are seen together, it points to a malfunction in the oxygen sensor bank 1 circuit. This could be caused by many things such as a failing oxygen sensor, leaking fuel injector, rich or lean conditions, or wiring issues. Generally the oxygen sensor codes can cause either a lean or rich condition as the car’s computer attempts to adapt without proper oxygen sensor readings. I recommend having a qualified technician, such as one from YourMechanic, diagnose the Check Engine Light and perform any repairs required.

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