devilz05

iTrader: (2)

My service engine light came on so I took the car to autozone to get it checked out. The first reader gave us a 0402 code (emission system malfunction) and I went to a second autozone and their reader gave a 0440 code (emission system malfunction). I already figured out that different readers give different codes but nevertheless the reading was the same. The guy showed me a booklet with possible problems and one of them was a loose gas cap which we tried and proved wrong. There were a couple of other things that could be causing the problem but it would require a mechanics hands, and I already forgot what they were.

Basicaly, I just wanted to know if a leaky exhaust could be the culprit here. I know for a fact everything from the cat back needs to be replaced soon so Im hopping that is what maybe causing the problem.

Any help will be appreciated

njmaxseltd

iTrader: (19)

Readers give P codes, they are the same on every like vehicle, readers don't change them. You have two issues going on, they may or may not be related.

P0402 - EGR Backpressure tannsducer or circuit fault. (interesting huh?)
P0440 - EVAP system leak. Thats a jackpot code! Could be just about anything. Try changing your gas cap first.

I can't help you with the EGR code, I've never heard of the backpressure transducer. Maybe someone with a FSM can help you out.

devilz05

iTrader: (2)

I know for sure that it was a 0440 code so forget about the 0402, that doesnt even make sense, I think the guy messed up when he was trying to remember the number. The 0440 I saw with my eyes, so I figure thats the safest bet.

Can a gas cap go bad out of nowhere? Seems pretty random that it would happen. Can putting in 93+ in a car that ran on 87 all its life cause this? What about a leak in an exhaust?

Thanks guys!

devilz05

iTrader: (2)

I noitced that below 40mph I hear this winding noise. Visualize a balloon full of air, the neck is being pinched so the air comes out slowly and you hear that trademark wooooooo noise. That is exactly what I hear. It gets a little louder as the car slows down and dissapears when the car is stopped. Im thinking that it is definetaly my exhaust starting to leak. Any thoughts?

devilz05

iTrader: (2)

anyone have a clue?

the_3d_man

iTrader: (1)

let's play "name that noise!"
maybe you have two codes?
and you might have a vacuum leak too. check all the vacuum hoses under your hood (might explain the noise...)
with the engine running open the hood and then stick your ear in there and listen. try reving the engine while you're in there and listen for the noise
just try this first. then come back and post more.

devilz05

iTrader: (2)

Will do....

Its only one code, though.

njmodi

iTrader: (4)

Check the seal on the gas cap - it's a quick easy fix - just buy a new gas cap and see if that helps. i.e. replace gas cap, reset ECU, and see if any codes reappear.

The backpressure tranducer refers to the EGR-BPT valve. It works in conjuction with the EGR valve to re-circulate exhaust fumes. Perhaps that valve is bad, or the vacuum line to it is bad, etc. Get yourself a Haynes - it covers diagnosis/repair of that part.

devilz05

iTrader: (2)

The gas cap clicks so I figure it should be ok. I think the A$$hat who sold me the car reset the ECU before he sold it so we wouldnt get suspicious. How likely is it that the service engine light goes off 2 days after I buy the car. I would consider getting a new gas cap and resetting the ecu but that will take a long time.

How long does it take for the ECU to pickup error codes after you reset it? Someone told me it could take up to a whole week. Also, if the problem is fixed, the service engine light goes off when the problem is fixed, correct? Or do you have to reset the ecu anyways?

njmodi

iTrader: (4)

Clicking has nothing to do with the rubber seal - that is just to let you know it's tight enough- but doesn't mean the seal is intact.

The ECU will post a code after it detects a failure several times over some pre-determined period. It wouldn't surprise me if the criteria for each code was different.

Similarly, if a problem is not detected by the ECU for a certain number of on/off/drive cycles, it will clear the code stored.

It is recommended that after any repair (to address a particular code), that the ECU be reset.

tomservo291

Depends on how quickly the ECU detects the problem... a lot of times things fail intermitenley (spelling?)

For example, when I had EVAP codes I could go anywhere from less then a day to two weeks before the ECU would pick it up again after resetting... but when I had a knock sensor code it would come back immediately after the first time the car was run.

Really depends on the part, the time interval could be instantaneous to weeks.

The codes you are getting sound about right for a few days after resetting the ECU, I would suggest quickly looking into your state laws about selling an automobile, they may require that the car must be inspectable (if your car cannot pass inspection with those codes, then you have may have a legit beef with the seller and may be able for either force them to fix it, or take the car back.)

devilz05

iTrader: (2)

With the code I have now is it recommended I take it to Nissan? There are so many things that it could be, I cant imagine a mechanic being able to diagnose the problem properly. This is already starting to look like a dent in my wallet, a wallet that is already dangerously thin.

njmodi

iTrader: (4)

Why don't you try replacing the gas cap as already suggested?

As for a mechanic or Nissan - there are excellent independent mechanics and dumb-a$$ dealers... it varies drastically from one place to the next... there is no reason that you HAVE to take it to a dealer - providing you can find a mechanic that knows what they are doing.

devilz05

iTrader: (2)

Will a Nissan dealership have gas caps on hand?