He is OBD2 so putting in a test pipe will still throw the code. Check the wiring to the O2 sensor behind the catalytic converter. You could then replace that one as it is only good for 10 years and "HOPE" it is the sensor and not the cat.
Or convert to OBD1 with a jumper harness..
But I bet this would work also....Universal o2 simulator single output [unv-o2sim1] - $40.00 : O2 Simulator, E-commerce