On my way home ses light came on, didn't hear a or feel any change in the car so since i had time i went straight to the mechanic to get it ran. came back P0420 "catalyst efficiency low" dude said it could be due to bad spark plugs and too much emissions overloaded the catalyst causing it to throw a sign, said i probably just need a tune up, which is good news, he cleared the code and told me if it comes right back then I need to hurry up and do the tune up. my car has 45k miles on it, accordingly to the owners manual you dont have to change the plugs til 100k but i guess not. well see if it comes back. have you guys have this happen, and what spark plugs do you guys recommend.

http://www.infinitihelp.com/Ownershi.../ITB00-054.htm

I doubt that your spark plugs have something to do with the SES.

thanks for the link, forgot all about that site. seems like this is a common code on max/i30's, I'm a see if the code comes back. has anyone had problems with the dealership reprogramming or updating their ecm, it seems this is something they should take care of free. since its the catalyst/emissions system.

Yes, it should be covered under the Federal Emissions Warranty, but whether or not a particular Infiniti dealer recognizes and honors it is entirely diffrent matter.

You may have better luck finding people who actually went to a dealer on this issue in the 5th Gen Forum. I had this issue for about two years but never gone to an Infiniti dealer to ask. For some reason the code and SES disappeared recently about a month ago and it hasn't come back......yet.

yeah i read a lot about this and the emissions warranty and of course i'm screwed. due to the fact that i'm stationed in Guam (this place sucks) and they have no emissions laws, the dealer won't honor the warranty. so i would have to pay $85 to update the ECM, plus diagnostic fee and if it needs more work i would have to pay for it. so the code is clear now hopefully it doesn't come back, if it does i'll update the ECM, in hopes i don't need a new cat, cause i could just wait 7 more months and ship it back to the states and make the dealer fix it there. i'm only at 45k miles.

I had the same problem on my first I30. They say if the reprogram of the ECu doesnt work, you have to replace the Y-Pipe. My local Nissan quoted me 600ish for the part alone(Front tube assembly as they call it) plus labor, new O2 sensor, etc. came out to $1,050 or so.

My best reccommendation is find the part in a junkyard, and install it yourself if you can(200-350 bucks). But.. another cheap/reasonable fix is replace the O2 sensor, and buy an aftermarket Y-pipe(300-450).

Just my $.02

Good luck

well the light is back on already, i'm a do the ecm upgrade, I hope that fixes it. if not Damn!

just thought of a question, if the cat is bad shouldn't there be some kind of symptons, changes in the cars behavior to tell its the cat.

You would have a rotten egg smell from the tail pipe.

well i haven't experienced that, from my understanding of this y-pipe failure is that the two pre-cats are not filtering the exhaust like they're supposed two and so the main cat is overloaded with emissions it can't take and your car pollutes the air. well if thats the case and there is no restriction of air flow then there really is no problem or damage being done to the engine. just a failed smog test which i don't have.

You're way off base. The main cat does not get 'overloaded with emissions' due to precat failure. People regularly remove the stock y pipe and replace it with an aftermarket one, totally eliminating the precats entirely without incident... I'm one of them.

My guess is that you have a bad rear O2 sensor that simply needs to be replaced.

you right, i didn't think about that.

Having the same problem too. I am going to replace my cat converter next weekend and hope that damn SES light goes away.

i haven't done anything since this happened and my car is fine, no changes, light is still on. i'm waiting to ship my car to the states and let the dealer fix it since its under the epa warranty.

Good luck w/ that.