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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 356 (Engine Controls And Fuel - 3.6L (LGX) - DTC P0446 To DTC P3436 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P2097 or P2099: Post Catalyst Fuel Trim System >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.

Fuel trim bias is used to keep the post catalyst air/fuel ratio within a predetermined range. This allows optimal catalyst efficiency under various operating conditions. The engine control module (ECM) constantly monitors how lean or rich the fuel trim bias is commanded, to determine if the fuel trim bias is greater than a calibrated amount.