Need advice on Code 420

najfario · #1 (**permalink**) 10-15-2006, 02:04 AM

have a 2005 2.5s with 67,000 miles. Warranty expired at 30K.

Had the "Service Engine Soon" Light come on yesterday on my 2005 2.5s. A rep at autozone checked the code and said its 420... O2 sensor/catalytic converter. He turned the light off. Said its usually a faulty sensor that comes one when it feels like and sometimes goes away. He said if it comes back on in the next 30 miles, take it to a repair shop. Got it new but have had issues. So far its has tranmission e-switch, throttle switch and fuel pump changed by dealer (under warranty). Now transmission is also giving a hard shift into 2nd.

For now...I am worried after reading some posts on precat failure and cat bing sucked into the engines resulting in misfire and f-ing up the engine. Is this common in all altimas or only the older models? And is this something nissan should cover even if the warranty is expired? My work involves driving a lot and i cant avoid it. Wondering if i should wait or drop it off at the dealer and grab my ankles? Thanks guys!

najfario · #2 (**permalink**) 10-15-2006, 11:21 PM

drove 70 miles so far - Light is not back on yet

bamashawn · #3 (**permalink**) 10-16-2006, 03:17 PM

I too have had the code 0420 present itself on my 2002 Altima 2.5S (actually in the shop this moring to get that fixed). I'm at about 110,000 trouble free miles... so this is the first issue for my Altima. If your car is still under 80,000 miles... then the catalytic converter is under a mandatory EPA warranty (8 years/80,000 miles). The code 0420 is actually something to the effect that the catalyst is below efficiency. That doesn't mean it's the O2 sensor... but it doesn't rule it out, either.

I would get my car to the shop for proper repair soon. Given that your car is still under 80,000 miles... your catalytic converter will be replaced with no cost to you (assuming that's what is wrong).

Good luck, but from what I understand about this sympton, you don't want it to go unchecked...

GPS · #4 (**permalink**) 10-16-2006, 05:49 PM

It means you need to relax and roll the windows down if it gets to smokey in the car.

Smoke3.5SE · #5 (**permalink**) 10-16-2006, 06:37 PM

I believe there was a recall on this, so they have to replace the precat for free. But I'm not sure if that includes 05s or not. If that light comes back you better take it to the dealer immediately. Some people have continued to drive the car with a 420 code only to end up with a FUBAR'd engine. I'm thinking your SES will be back because your precat must be going bad for it to come on in the first place.

ducz24 · #6 (**permalink**) 10-16-2006, 07:18 PM

i just had my 02 2.5s done for the same code bout a week ago and it was under the 8yr/80,000 miles warranty and didnt have to pay anything because the code P0420 is for emission recall. i would take it to the dealership ASAP. dont wait for the code to comeback again. i tried that, and i found my car dying out. dont wait for that. next thing you know you need a new engine. search! there are alot of post here regarding this code and all of them says to take it to the dealership ASAP.

dnvrfan · #7 (**permalink**) 10-17-2006, 02:51 AM

Yea please do not wait to go to the dealer on this. Much cheaper to have this fixed then to have to replace the engine. Either that or get some headers. You will not regret it.

najfario · #8 (**permalink**) 10-21-2006, 01:20 AM

So went to dealer, they checked it out and said that the ECM needed to be reprogrammed and that was it. They said that that it was wrong fuel mixture coupled with overheating catalytic converter (never heard of over heating cat) that was causing the "Service engine soon" light. They did confirm that the Cat-converter was under warranty. And they did not charge me anything. Sweet! Thanks for the input guys!

NOTORIOUS170 · #9 (**permalink**) 10-21-2006, 12:20 PM

man at first i thought this was a smokers post. good to hear it didnt cost u a thing.

bamashawn · #10 (**permalink**) 10-27-2006, 06:26 PM

Since my Altima was over 80k miles... I had to pay for my cat replacement... and it wasn't cheap. But, it's amazing the difference it has made. Not only am I getting better mileage out of a tank of gas... but the power is more linear than before. Apparently my cat was getting rather clogged up, so the engine wasn't able to breathe as well. Alls well now (I hope) and plan to keep the car another 110,000 miles. At 220,000 miles I'll look in to the new Altima in the market then...