For all 5th gen maxima owners with less that 80k miles on their Max and have pulled a P0420 code (Failed Cat converter), my story should be of help to you. Way back at 68k miles my SES light turned on and eventually got myself a decoder and found out it was my catalytic converter that failed (Cali spec). I brought the max to the local dealership (Nissan/Kia world of Denville, NJ) and told them about the code to confirm the problem. They proceeded to treat me like I had no idea what an engine looked like and said "people often pull the wrong code from the car". Surpise!! they pulled a P0420 code. They proceeded to tell me that the ECU needed updating. Cost = $200. Got the service done and drove the car. 1 week later, the P0420 code came back and returned the car to the dealership. They said it was my catalytic converted that failed and that it needed replacing. Hmm that sounds very familiar!!! Cost = $ 1100 parts/labor. I promptly took my key as said seeya. I opened up my warranty book and found a very clear passage that said that the ECU and catalytic converter on my Cali spec Max was covered under a 8yr/80k mil warranty. I called the dealer and said that they only warranty the cat and ECU under 5yr/50k miles. Discouraged, I called Nissan1 customer service and told them of my dispute. After much phone tag and run around they finally said "our warranty dept. said the ECU and Cat converter are covered under 5yr/50k miles". At this point I was losing hope, so the last step that I could take was to WRITE A LETTER TO THE CALI AND FED EPA dept. and sent them copies of all my documents and phone contacts at Nissan1. To my surprise 2 weeks later I receive a letter from the EPA saying that they are investigating my dispute with Nissan and gave me a copy of the letter that they sent. 1 week later I got a phone call from the same Nissan1 rep saying " our warranty dept. COVERS THE ECU AND CATALYTIC CONVERTER FOR 8YEARS/80k miles". I was surprised, happy and very sad that Nissan didn't want to own up to their responsibility for the repair. I received a full refund of the ECU update and currently am having my cat converter replaced (with another dealership). I highly suspect that Nissan is doing this to many others who have cat failure and do not know that they can write to the EPA. I think that they believe that fixing my problem will eliminate any future class action suits because I saw a number of people with P0420 problems. My advice after all this headache is to confirm with a dealership that the problem is definitely a cat failure and get it in writing. If they dont fix the problem find a dealership that will. If that doesn't work, take the same steps I did. I feel this is one victory for the average hard working Joe. GOOD LUCK all.

 

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