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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1051 (Engine Controls And Fuel - 6.6L - DTC P02E7 To DTC P0699) >> DTC P0401 or P0402 >> Circuit/System Description

Circuit/System Description

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The engine control module (ECM) tests the exhaust gas recirculation (EGR) flow when the EGR is in operation. EGR desired flow is compared to EGR actual flow. If EGR flow is lower or higher than expected DTC P0401 or P0402 will set.