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Ron Z.
Ron Z., - Nissan Tech -
Category: Nissan
Satisfied Customers: 17792
Experience:  18+yrs experience. State Inspector and Nissan Diagnostics
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I have a 2004 Pathfinder/Armada with 209436 miles. The

Customer Question

I have a 2004 Pathfinder/Armada with 209436 miles. The Service engine soon came on while driving, What is wrong with the car?
JA: Do you have the trouble code? Do you have a code reader or scan tool?
Customer: No sir. I don't have any special tool to do just that.
JA: I'll pass this info along to the Nissan Mechanic so that he can get you a quick fix. Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes sir if no special tools are required. Otherwise I have to weigh in renting tools that is required or bring the car to a mechanic.
JA: Anything else you think the mechanic should know?
Customer: I am sure the scheduled oil change is coming up in 2 weeks and of course need some add on such as water, freon, etc.
Submitted: 2 months ago.
Category: Nissan
Expert:  Ron Z. replied 2 months ago.

When the Service Engine Soon light comes on, this is the on-board computer's way of telling you it sees a problem in one of the monitored systems. Unfortunately, there are literally 100's of parts and sensors monitored in various systems, and to take a "guess" as to which part/sensor in which system is faulty, is virtually impossible. However, if you are not experiencing any drivability issues such as skipping, stalling, shifting problems, etc, then more than likely, the problem is going to lie in the EVAP (emissions control/recovery) system. Very commonly, this could be a faulty, loose or missing fuel cap or even putting fuel in while the vehicle is running can set the light. Check the underside of the fuel cap for any cracks or signs of defects that may keep the cap from sealing correctly. If there are any doubts about the inspection of the cap, replace it. Keep in mind, you will need a cap that meets OE Specs. Those "universal" or "locking" fuel caps sold at after market parts stores do not meet OE specs, and will not seal the system correctly. Check the top of the fuel filler neck for any signs of damage or debris. Check under the vehicle, around the rear areas of the vehicle, looking for any vacuum lines that have dry-rot cracks, holes or loose/missing connections. If these all check out, then the best thing to do at this point is to have the Diagnostic Trouble Codes (aka "p-codes") read from the on-board computer. These p-codes are what is used as a "starting point" for the diagnosis and will tell which part/sensor, in which system, has the fault. There isn't a Mechanic on the planet that can tell you what is wrong with the vehicle just by "looking" at the Engine Light. Every single Mechanic's first course of action WILL be to obtain the p-codes. It's standard diagnostic procedure. Once you get these p-codes you can more accurately and efficiently diagnose the problem and then make the correct repair. You can have these p-codes read FREE (except in California) at any local "big chain" part store (ie. AutoZone, PepBoys, Advanced, etc). If you found this answer helpful, please help me by leaving a rating using the "stars" at the top of the page or click 'accept'.
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Expert:  Ron Z. replied 2 months ago.

Hi! I noticed this thread was still open and you did not leave a rating , so I wanted to check in and see if there was anything else I could do for you on this issue? Did you have any other questions? Did you have the p-codes scanned? If you have no further questions and simply forgot to leave a rating, please take a second and use the stars at the top of the page to rate our Q&A session. Thank-you!

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