Check engine light turned on with code PO171, where are the sensors located?

2015 BUICK LA CROSSE
28,380 MILES • 3.7L • 6 CYL
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JWILLI
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Do I need to replace all four 02 Sensors? I replaced the MAF sensor and the upstream and downstream Sensors on Bank 1. the check engine light came on again the code is PO171 bank 1 and 174 bank 2. How can I fix this problem and where are all the Sensors located?
Jan 8, 2022 at 5:31 PM
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SQM
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Hello,

Keep in mind this code can get triggered due to faulty wiring for the oxygen sensor as well as other components.

There are oxygen sensors located after the catalytic converter on the exhaust pipe.

Best course of action to take a deeper dive and trouble shoot this rather than just replacing parts.

I have attached the troubleshooting guide for the code P0171 and P0174 below. Got through the procedure as that can help you determine the issue.

Please let me know if you have any questions.
Thank you.
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Jan 8, 2022 at 8:48 PM
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JWILLI
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Thanks for your quick response.
Jan 9, 2022 at 5:59 AM
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SQM
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You are welcome. Let me know how it goes.
Jan 9, 2022 at 10:10 AM