I have about 40K on my X. Twice, during the past week, the "service engine soon" light has come on. Both times, I have tried to read the embedded code with my reader, but it doesn't find any. I can erase whatever code is stored with my reader. I'll probably have to take it in to the dealer.

Question......does Nissan use proprietary codes on some of the error codes, which would require taking the vehicle into the dealer, or purchasing a expensive reader?

No, almost everything is OBDII after '94.

Sounds like your reader is having issues.

If you want to make changes to the ECU etc. only a dealer has the ConsultII (I think that's what it's called.) of which can do it.

Try your local autoparts house.

Simple code readers may not be able to read codes that are pending. Go to an auto parts store (Auto Zone will read the codes for free). They will have a scan tool (better than a code reader) which can read both pending and hard codes. I suggest not clearing the codes, as that information can help a qualified technician diagnose and repair the vehicle. In fact, most auto parts stores will not clear the codes for you.

All manufacturers have codes specific to their company. They are also required to have generic codes that are universal to all manufacturers. Codes that start with P0xxx are generic codes. Some of the most common P0 codes are emissions related. Codes that start with P1xxx are manufacturer specific.

In the near future, all On-board diangsostic systems (OBDII) will be running on a Controller Area Network (CAN). All manufacturers must switch to a CAN-compliant system by (I think) the 2008 model year. Not all code readers and scan tools are CAN compliant.

If the girlfriend/wife recently got fuel, check yer gas cap. Nice and tight...

My scan tool (computer based, usb connection) couldn't connect to the Xterra either. However, there is a way to display codes with no tools at all. turn ignition on, wait 3 seconds, completely depress and release gas pedal 5 times in the next 5 seconds, and there is some other step I think.. the code is displayed in a sort of morse code fashion by the "service engine" light on the dash...

Or you could go to AutoZone and have the codes read for free...

My code reader works fine. Used it a couple of times on my Nissan, my father's Nissan, and a handful of different vehicles for friends & coworkers. Never had an issue reading codes.

Dad's got the same thing on his 05 right now. His nice code reader would not read it. he took it to the auto parts store and they read it as a genaric PP0021 I think, cant remember for sure. Which was a Timing issue of sorts. Sounded like a issue with the cam sensor. Get it checked maby if you got the same code we could narrow it down together.

-Blue02