Buick Repair Questions? Ask a Mechanic for Answers ASAP
Sorry to see no one seems to want to tackle this one but I will try to help.
P1640 is an internal PCM/ECM ram/rom error. By standard diagnostics this will lead to ECM replacement. If this is still coming back after replacement than you likely have a bad power or ground to the ECM
P0131 & P0171 indicate lean running engine on bank one.
As far as the quad driver, sometimes, even factory scanners like the Tech2 can missinterperate this and show a fault when there is none depending on the model.
You must figure out the P1640 first.
Hope this helps