P0174: System Too Lean (Bank 2)

The normal air-fuel ratio in an internal combustion engine is 14.7 parts for the air and 1 part for the fuel. When you have an air and fuel mixture with this ratio, it means your engine produces power normally. When you step on the accelerator, your vehicle will accelerate as it should. But if you ever have over 14.7 parts of air, then it means you have too much air in the mixture. This is a lean condition for the ratio.

You won’t immediately know that you have a lean air and fuel mixture. But you can watch for certain symptoms which could prompt you to investigate the situation. The most common symptoms include rough idling, a Check Engine illuminating light on the dashboard, weak engine power, engine misfires, and engine coughing. If you experience any of these possible symptoms, then use a diagnostic scanning tool on your powertrain to see which diagnostic trouble code is given.

If you receive code P0174, then it means you have too much air in Bank 2. This is considered a moderately serious problem. You can drive your vehicle temporarily but only do so to get to an auto technician. Don’t procrastinate and avoid going to the mechanic altogether because it could cause worse problems for your engine. You could end up with damage to the internal components of the engine due to overheating.

Do not automatically assume that you must replace the air-to-fuel ratio sensor and oxygen sensor. There are so many possible causes of a lean mixture problem in Bank 2. You could have an exhaust leak, clogged fuel filter, dirty fuel injectors, bad fuel pump, vacuum leaks, or a dirty mass airflow sensor. If you are not sure how to investigate these components, then have the auto technician do that for you. It is very easy to misdiagnose the cause of the problem if you are inexperienced.

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The estimated repair costs depend on the reason for the problem. For example, if you only need to clean your mass airflow sensor, then that’ll cost you about $100. But if you need to replace your fuel pump, then you’re looking at anywhere from $1,300 to $1,700. That is why it’s important to bring your vehicle in for regular checkups. Then you can detect these problems before they arise.


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