The 2014 Buick Regal has double overhead cam (DOHC).
The 2013 Buick Regal has double overhead cam (DOHC).
The 2011 Buick Regal has double overhead cam (DOHC).
The 2003 Buick Regal has overhead valves (OHV).
The 2004 Buick Regal has overhead valves (OHV).
The 2002 Buick Regal has overhead valves (OHV).
The 2001 Buick Regal has overhead valves (OHV).
The 2012 Buick LaCrosse has double overhead cam (DOHC).
The 2012 Buick Verano has double overhead cam (DOHC).
The 2012 Buick Enclave has double overhead cam (DOHC).
The cam sensor on a 99 Buick Regal is located behind the rear cam bearing cap. It monitors the rotation of the cam and relays information to the vehicle's computer.
The 2.8 engine doesn't use a cam sensor.