Found it on another site. Thanks Google and dadster.
This is how you find out why your Service Engine Soon (SES) light is on and how to reset it. No tools required!
In car ECM Diagnostics/ECM Reset procedure:
1) Sit in the driver's seat.
2) Turn the ignition key to the ON position and wait three seconds. (Do not start the car.)
3) Fully depress and release the accelerator pedal five times in less than five seconds.
4) Wait exactly seven seconds. Fully depress the accelerator pedal for ten seconds until the SES light flashes.
5) Release the accelerator pedal and start counting flashes to obtain the four-digit trouble code.
Long flashes (0.6 seconds) indicate the first digit of the code; count the blinks one through nine and write down the first digit. (Ten blinks indicates a zero.)
The next three digits follow in turn in the same fashion except with faster blinks (0.3 second) and a 1.0-second pause between digits.
The ECM code repeats intself until you turn the ignition key to the OFF position, at which point the ECM resets itself to standard get-in-and-drive-the-car mode.
You can look up the trouble codes in the ESM/FSM; there's a bunch of them. In the ESM, refer to page EC-639.
Additionally, if you get four blinks of ten (0000), the ECM is indicating no malfunction.
You can clear the code (and the annoying SES light) by holding down the accelerator pedal for more than 10 seconds while the SES light is blinking. When you release the pedal, the ECM erases the trouble code(s).
How-to: Read and Reset Check Engine/Service Engone Soon Light - Nissan Forums: Nissan Enthusiast Forum