One problem related to gas recirculation valve (egr valve) has been reported for the 2001 Buick Regal. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Buick Regal based on all problems reported for the 2001 Regal.
My wife went out to start the vehicle after it had been sitting for 2-3 days in 0-20 degree temperatures. Upon turning the ignition switch she heard a loud explosion sound, saw the hood bulge, and saw smoke billow out from the sides. She immediately removed key, exited the vehicle, and asked me to come out to the vehicle. Upon opening the hood we found pieces of the heat shield, and plastic intake manifold scattered through the engine compartment, along with the oil fill cap, which had been blown off.