2008 Altima Coupe Issue

[jcolvin]

Hello All.

I could use some advice regarding my 2008 Altima Coupe 3.5SE.

Two days ago, the CEL came on. I plugged in my BT code reader and it came back with P0420. Now, this code points to Catalytic Converter inefficiencies or bad O2 sensors etc. I'm not the best car mechanic, so I took it to a buddy and his shop.

They ran tests and checked underneath after running for a little bit. He advised me that the vehicle has a manifold leak and that's what led to the eventual P0420 code. I trust my buddy at the shop. He's really more so family(father-in-law to my brother). Given the situation, it will need manifold leak fixed, new CC's, and O2 sensors.

With this information, I was advised it may be better to get out from under it and pursue another vehicle. What are your guys' thoughts on this?

[fyarf]

i'm no expert either, but unless a manifold leak somehow ruins catalytic converters and burns out an O2 sensor, just fix the manifold leak and go from there.

On a personal anecdote, my CEL came on and i got a code (cant remember which one now, but something about exhaust leak or MAF sensor), but i freaked out. Turns out the gas cap seal had gotten unseated and caused the light. drove it after the reseating the seal for a couple of days and the light went off.

[jcolvin]

Thanks fyarf.

Again, I'm not much of a genius when it comes to car diag. I did hear about that gas cap thing. I checked mine and ensured it was clicked in properly. Seems like if that were the issue, my light would have gone off already.

[fyarf]

It takes up to 100 miles of driving after the gas cap is secure for it to go off, or you can go to auto zone and clear it and see if it comes back. Like i said, check the seal around the threads and make sure it is seated correctly. Otherwise, mechanic it is.

[Letsjustkill]

The 3.5s were well built what was their reasoning for get out from under the car because of an oxygen sensor it just seems odd?

[fyarf]

He said they told him manifold leak was the reason to ditch the car, but the code seems too ambiguous to just ditch it. I say get a second opinion before jumping ship on the vehicle if everything else is good. God forbid it, but if you have a local dealer service center you feel you can trust, get them to diagnose it, or a different trusted shop that specializes in imports, or maybe even a nissan/infiniti shop.

[seldomseen]

Don't be cheap....take your car to a reputable Nissan dealership to properly determine the problem and to get an estimate of the repair cost.

[fyarf]

Don't be cheap....take your car to a reputable Nissan dealership to properly determine the problem and to get an estimate of the repair cost.

Seconded. They'll diagnose the problem, then you can shop around for pricing on that fix.

[jcolvin]

Thanks Fella's. That's my goal for today.

Going in for service at dealership to get it diagnosed. What's odd now is that the light has turned itself off. Because this happened, that would make me believe it was in-fact the gas cap issue. Still, I'm going in to get it checked out to be sure.

I had spoken to one fella and he said because the light was off, they couldn't diagnose the issue. I told him the codes would still be logged in the computer. He denied that. I call BS on that right there.

[justeller]

The code should still be in the history. Although a lot of inexpensive scan tools will just scan current codes and not stored codes. 9.9 times out of 10 a manifold leak is not going to reseal its self (if it was the gasket, i'll give you a 1% chance of this happening) nor would it ruin O2 sensors. When I worked at Advance Auto for ten years The P0420 was the most common code when doing scans on customers vehicles. It is either your gas cap (if it comes back on try getting a new one) or I would say you have a downstream O2 sensor that needs to be replaced. Go to Nissan, have them scan the computer, and then they can actually tap into your O2's to see if they are working correctly. A higher end ($150-$200 and up) scan tool should be able to read your O2's and make sure they are working. Trick isn't finding the scan tool, it is finding someone that half knows what they are doing.