Conditions for Clearing the DTC

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

A current DTC P1631 will be when a correct fuel enable password is received.
A history DTC will be cleared after 40 malfunction-free ignition cycles or when a scan tool is used to clear DTCs.