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2011 Chevy Silverado 4x4 Running Rich Due to High Alcohol Content in Fuel

Model: 2011 Chevy Silverado Fault Code: P2177 Posted: 2016-12-04 14:00

Hi, I own a 2011 Chevrolet Silverado 1500 4x4 and recently received diagnostic trouble codes indicating that both Bank #1 and Bank #2 are running rich. My engine control unit (ECU) has flagged this issue as being caused by an excessive alcohol content in the fuel. I have been using Shell High Test Fuel consistently, which I believe contains 0% ethanol based on product labeling. However, the ECU suggests otherwise — so I'm wondering how this discrepancy could occur. Could there be a misreading or a misunderstanding of the fuel composition? I want to confirm whether my vehicle is actually experiencing an alcohol-related issue that affects fuel mixture calculations.

Related fault codes
P2177
Comments (2)
Anonymous 2016-12-04 14:07

Can you clarify how your ECU concluded that there's too much alcohol in the fuel? Is your Silverado equipped to run on E85 flex-fuel? Have you or someone else filled the tank with E85 fuel? It's important to note that most conventional gasoline contains around 10% ethanol, so a high reading might not be due to incorrect fuel but rather an ECU misinterpretation or sensor issue.

Anonymous 2016-12-05 23:14

If your scan tool supports it, try performing a fuel alcohol percentage reset. This can help recalibrate the ECU's alcohol detection and may resolve false readings related to fuel composition.