yup, that's the only code that comes up. my friend told me to check the exhaust manifold bolts up to the cat bolts for a leak. i'll try all that and den check nissan and see what they got. thanks again, rodIs P0420 the only code? It appears that the code is triggered by comparisons of the oxygen sensors before and after the converter. In addition to a bad converter, the oxygen sensors and the electronic control module (ECM) programming could be suspect. A web search suggests that Nissan Technical Service Bulletin NTB02-092 may apply. I looked at the TSB and it shows that reprogramming the ECM may be required (this is a Nissan job). You might want to contact the dealer and see if the TSB applies. You're outside the emission warranty mileage for a free reprogram but they may offer you a break since you have a new converter. By the way, the TSB says that you do not replace the converter.