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Service Engine Soon light keeps coming on

I have a 2009 Nissan Maxima with a little over 57,000 miles on it. I take it in and get all the checkups and oil change every 3000 miles. Recently I have had the Service Engine Soon light come on so I called my mechanic in town to take a look, he could find nothing wrong and cleared the code. About a month later it came back on again, this time I took it to my husband’s mechanic and the error was an emissions error code but he could find anything wrong. He cleared the code and I was on the road again. After about a day the light came back on, I have not taken it anywhere and the light is still on. I don’t want to take it to my Nissan dealer and spend a fortune and then a day or two have it come back on. Has anyone else encountered this problem?

First, are you sure it is a SES (Service Engine Soon) or could it be a CEL (Check Engine Light)? Check your owner’s manual.

On the display it comes up as Service Engine Soon

Firstly, it is safe to drive.

Drive it to the local parts store and have them read any stored fault codes. Many parts stores will do this for free.
Post the codes here.

Wild guess: it’ll be a P0420 or 430. If I guessed right I’ll explain what that means.

The service engine soon light means the same thing as the check engine light.
I believe GM also calls it service engine soon

@CLD for future reference, the check engine light (or SES, or whatever you want to call it) doesn’t really come on for no reason. The fact that the mechanics couldn’t find anything wrong didn’t mean that everything was okay at the time that it did come on. Certain conditions were met to cause the light to come on.
I trust you weren’t charged to clear the light the first two times?

CLD. as stated above, many parts stores will read the code for free, but they will tend to tell you what they think is the problem and what parts you need to buy. Ask them for the cash register printout for the code. It will have all the information that they will give you, but at the top, it will show the actual code and it will be a P followed by 4 numbers, i.e. P0410 or something like that. Tell us that code and forget the rest. we may comeback and agree with the rest of the stuff on the readout, or maybe not. But you will get a better idea of what is wrong.

Thanks I have tomorrow off so I will go and have them give me the code and will post back

Okay so I was finally able to get my car in to see my mechanic. The code that came up is P0448-EVAP. He spent a Hal hour checking everything and found nothing and I am $55.00 poorer. Thoughts

P0448 - Evaporative Emission Control System Vent Control Circuit Shorted.

The mechanic didn’t do any checking of the EVAP system ? What did he/she say ?

Chances are that until the problem is corrected that the SES light will be back.


" Has anyone else encountered this problem? "

Apparently this is a common Nissan problem.


Looks Like You’ll Probably Need To Have A Revised Vent Control Valve And A Filter Kit Installed. Check With Nissan To See If Your Vehicle Is One That Needs This Updated Repair.


I thought emission issues had an extended warranty for most cars? Ur car is an 09? That has a 100k warranty, right? Or maybe that’s Hyundai?

You might be just overfilling your gas tank. Is the light coming on shortly after you fill the tank? Are you adding fuel after the handle first shuts off?

The gas tank needs an air space at the top of the tank. If you fill it all the way to the top, then the fuel expands when it gets a little warmer in the tank, it goes down the vent tube to the charcoal canister and saturates it. That causes issues with the vent control valve that your code is identifying.

Are you sure its a P0448 and not P0446? Typically it returns the P0446 and the best thing to do with that is to just stop overfilling the gas tank. The charcoal canister will dry out and the problem will go away. If it is truly a P0448, it may be too late for the vent control valve and it may have to be replaced.