You will need to install the correct catalytic converter designed for your Nissan Pathfinder. The reason your Nissan Pathfinder may have passed previous smog checks in probably because smog inspection regulations, as they pertained to the catalytic converter, were not followed strictly. Smog technicians were simply visually ensuring the catalytic converter was present and that it appeared to fit the car being smog checked. If the fit looked right, the weld (if welded) was clean, and the number of CATs required were present, the vehicle passed the CAT visual inspection.
Today however, with the new STAR smog check program, things have changed a bit. A smog station and/or smog technician can now lose his/her STAR status if smog inspections are not carried out to a "T" and catalytic converters are not visually inspected for proper model number (CARB number for aftermarket CAT) and fit.
As such, it appears the smog inspector in this situation inspected the model number and EO (executive order) number of the CAT installed on your Nissan Patherfinder and found it is of the incorrect model. This is automatically considered a "tamper". The correct catalytic converter will need to be installed before your Nissan can pass the smog inspection.
