service engine soon light returns codes p0430 and p0420

In early Spring 2013 I had my Nissan stall a couple of times in a day and then not start after fueling up. Start attempts would produce a rough idle unable to maintain without starter engaged. Vehicle was towed to Nissan repair and found that a recall on the ECM relay was due. Repair was made and vehicle was running fine...until September 2013. I got a very common P0463 code for the fuel sensor followed by P0430 & P0420 indicating catalytic converter below efficiency. I had purchased the vehicle used and with an extended warranty from Ford. I used this to fix the fuel sensor and hoped that that repair might clear the codes P0430 & P0420 based on some internet searching and dealer input. Those codes came back the next day after fixing the fuel sensor. I am finding that many Nissan owners experience the P0420 & P0430 codes very soon after the ECM relay begins failing. Because the ECM controls engine performance and many functions it could cause rich fuel mixtures and improper ignition timing that would prematurely damage catalytic converters.

The cost for repairs for catalytic converters can easily cost over $2000. I had the rear drive shaft replaced due to leaks at the rear yoke (dealer service says that is typical for 80,000 miles). I am having quality control issues such as rear door latch failure, and squeaks and rattles. So, a recall item with a strong link to the expensive catalytic converters is not getting corrected or admitted as a link by Nissan. Add that to the very frequent and expensive failure of the automatic transmission due to cracks developing in the engine radiator. I can see that owning a Nissan is an expensive undertaking that I have not faced with any of the used cars I have owned in my lifetime with far greater miles. Without Nissan supporting quality issues I will soon be parting with a vehicle that has many great attributes that can't outshine poor engineering and quality.

Had trans and radiator go out, nissan fixed that and one day later ses light came on. I brought it back to the dealer said it was the fuel sender unit and the cost would be $451.00. not covered by nissan. something is wrong with this model year. I was lucky the trans and radiator were covered but I have spent $ on smoke sensor $284 with 38000 mi U joint $321 with 41000 mi wheel hub assembly $300 with 65000 mi clamps for the muffler pipes with 66000 $20 all at local shops. these are problems that may or may not occur in vehicles but the fuel sender unit I do not think so. p.s I have never had any of the problems listed with any other vehicle I have owned. Am I that lucky or is there a real issue with the 2005 xterra which I bought new in December of 2005 so the vehicle is only 6 years old. Nissan needs to step up. The vehicle when it is on the road does give a tight ride, no rattles.