I keep on getting the service engine light on. When I have it checked out at the auto parts it gives me a "0420" code. I have been told that it is an O2 sensor pre-cat. Well it has happened 3 times in the last 2 weeks. I called my Nissan service guy and he said that it is one of the O2 sensors and reprogramming to the latest software on the computer.
Anyone have this happen to them?
I have the Cattman catback exhaust and cold air intake in right now...and thats it.

 

The exhaust shouldnt matter. But Ive heard about the reprogramming. Get that done and see how it holds up.

Dont want to run into service issues once that s/c goes in. Believe me, they wont touch it.

Dixit

 

Tahnks Dixit...it goes in tommorrow.

 

I have a pretty similiar problem. I dont know if it's my exhaust or not, but I have the cattman exhaust as well.

 

I will let you know if it take care of the problem after the dealership does the reprogramming.

 

Awesome! Hope it fixes it.

 

It's the 3-way catalyst code. Seems to be common on the 2K's. The parameters or window of normal operation of your emissions get too small and require reprogramming by the dealer. My light had been coming off an on about every month on my car.

 

Did the reprograming take care of it?
Do you have a upgraded exhaust system?

 

reprogramming fixed it so far(2 weeks)

Stock exhaust system-

 

Latin, what does your exhaust system consist of and are you cali spec?

 

I have done the entire Cattman exhaust except for the muffler. That is the factory unit.
Cali spec...I don't know. I don't think so. I have the 2 center plugs on the front of the engine. I think it is fed spec.

 

Stock cat or RT cat?

 

RT cat

 

I've got a test pipe, but I'm still real interested to see how it goes.

 

I will post when I get it back.

 

I have completely stock, sad I know , 2000 SE 5spd. I got service light twice in a week, too. I just bought the car 2 weeks ago!

The codes I got were P0400 and P0171. I'm guessing this is the same problem? Is the ECU reprogram covered by the 8/80000 warranty? Will the dealer insist on running the engine diagnostics before performing anything? Will I incur any other charges?

The car runs absolutely beautifully, tho. The gas milage seems fine as well.

I'd appreciate any help or comments.

 

The dealer will definitely run a diagnostic check before doing anything, and they will more than likely not cover it under the 8/80 emissions warranty. Not unless you have a really cool dealer. They will more than likely replace an 02 and reflash your ECU.

 

Well, here is my update:
It went to the dealer on Wed and got the computer reprogrammed, but they said that they had some problems with static (don't know if they knew what that is), I brought the car home and Thur morning after driving a little while. The SE light is on again. So back it went, I still have not heard what they have to say.
Hopefully I will here something first thing tomorrow.

Oh I have the exhaust all upgraded and a CAI. (Cattman)

 

I got the same problem... I think the same code (i'll have to check). Dealer said they download the newest ecu program and updated it into the car. Problem has gone away

 

Here we go again. I picked up my car today and it turns out that they can;t do anything else for me.
But this is what they gave me from the service manual.

"The ECU monitors the switching frequency ratio of the front and rear heated oxygen sensors.
A warm-up three way catalyst with oxygen storage capacity will indicate a low switching frequency of the rear heated oxygen sensor. As oxygen storage capacity decreases, the rear heated oxygen sensor switching frequency will increase.
When the frequency ratio of front to rear heated oxygen sensors approaches a specific limit value, the warm-up three way catalyst malfunction is diagnosed.
Malfunction is detected when warm-up three way catalyst does not have enough oxygen storage capacity."

So I am thinking that I need to move the back O2 sensor back a little bit to increase the amount of oxygen between the three way cat.

See I got the exhaust form Cattman and there was no port for the rear O2 sensor and I had to add it. It sounds like I may have placed it to far forward.

What do you guys think?