The Engine Control Module (ECM), often called the engine computer, in a 2001 Pontiac Bonneville is typically located
under the hood, near the firewall on the passenger side. However, its exact position might vary slightly depending on the specific engine and options installed in the vehicle. It's usually attached to the inner fender or a bracket nearby.
To be absolutely certain, check your vehicle's owner's manual. A diagram showing the location of major components, including the ECM, should be included. Alternatively, a quick online search for "2001 Pontiac Bonneville engine computer location" with images may also reveal its placement.