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Home >> Buick >> 2009 >> Allure Super >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 5.3L - DTC P0420 To DTC P3449 >> DTC P0641 or P0651 >> Circuit/System Verification

Circuit/System Verification

Ignition ON, observe the scan tool 5-volt reference 1 and 2 parameters. The reading should display Circuit OK for a normally operating system.