All,
This might be long, but I figure it needs to be for a proper update. Back on page 2-3, I'm the dude that brought up seafoam and the old "italian tune up". Those tricks worked, but only for about a month. In the end, I opted for replacing the cats with OEM replacement parts from Davico. One side in January of '16, and the other side in November of '16. Flash forward to this weekend, and the CEL lights up, and P0420 gets displayed AS I'M DRIVING AWAY FROM AN OIL CHANGE! Went back, they cleared the code, and now I'm playing the waiting game. If the code comes back, that will mean that the earlier of the two replacement cats will have gone bad in just about 21 months. The truck currently has 115,000 miles on it (roughly). We've owned it since 73,000. So in 42,000 miles of driving, we've replaced: high pressure fuel pump, low pressure fuel pump, timing chain, left catalytic converter, right catalytic converter, power steering pump, transmission coolant lines (rupture that left us stranded on the highway, and had to be towed to the dealer), rear suspension pump, new battery (replacement Infiniti battery was put in just before we bought it based on manufacturer sticker, and lasted maybe 11 months) and put on some new tires.
Quite literally, I will never buy anything made by Nissan ever again.
Wow. Just wow. Sorry about your cat getting bad again. And sorry about the list of things you have had replaced on your QX. I hope your extended warranty paid for most of those things on your list. Did your extended warranty cover a lot of it? Or did you have to pay out of pocket?
I see you used the aftermarket cat manufactured by Davico. I personally had wondered about the longevity of that cat. I heard they will not last as long as OEM. And I have been hoping to see someone who will provide a long term road use update. You are the first person I am seeing so far that the cat seems to be failing.
Based on this thread from page 2, and from this your recent post, it seems you have had the new aftermarket cats on your car for about 20,000 miles and now it is throwing a SES code like your OEM cat did a while back. So, it is very possible that your aftermarket cat is toast! So your aftermarket cat lasted only about 20,000 miles. Now others with aftermarket cats will have to watch out for that mileage of use to see if their lights too will come up or not.
I remember when I was going to change my cat and wanted to buy the same aftermarket cat you bought. My mechanic told me not to buy aftermarket. He said for a car like this QX he does not trust that the aftermarket will last as long as oem. He had said if the oem is failing just after 60,000 miles for some and say 80,000 for others and me failing at 100,000. He said that for this car, he strongly recommends I make the sacrifice and buy OEM. So, I did that.
I hope you replaced your oxygen sensor when you replaced the cats. I am just going to assume that you replaced the oxygen sensor on each cat that you had to replace since it is expected to do when we replace a cat.
I must say that it cost me $1,350 to replace my bad cat with a OEM catalytic converter. I bought the cat, gaskets, oxygen sensor, all new nuts and bolts and paid for installation. Everything cost me $1,350 out the door.
It seems another member here posted his estimate of how much he spent to replace his cat using that aftermarket cat. I think he wrote he spent about $1,350.
He spent $1,350 to get aftermarket cat.
I spent $1,350 to get OEM cat.
So, if anybody wants to replace their cats, try to get an estimate of the cost and go with OEM if the cost is almost the same or not too far off from each other to justify going with aftermarket. Go with OEM which will be more peace of mind and most likely last longer than aftermarket.
As for you, I do not know how much was your total cost to replace that cat that failed you recently. If you spent about $1,350 to replace that cat, then I say I wish you had gone with OEM instead.
Well, I wish you luck and keep us posted with another update again if you finally figure out if the aftermarket cat is toast for real or not. That was some very useful information you just shared. I hope others can always share like this to help others.
And don't feel bad about your Nissan. There are just some bad seeds in every make and model of vehicle car out there. Maybe you picked a bad one. I have not been too lucky with my own QX either. BUT I have been lucky with my own Nissan. I have my 2008 Maxima which has had its own problems, but it is the most reliable car I have ever owned and it is my pride and joy for cars. Car treats me great and at 219,000 miles, it is just as fast and maybe even faster than my QX and let us not even talk about how it handles on road trips. All I say to others is "Catch me if you can". Nobody can keep up. Be it Porche, Mercedes or BMW.