The code if not cleared will show up when the engine is started but will go away if all is good. If it is an active code then the unit will will have all the dash lights going crazy and depending on the sensed fault will either not be effected as in an e-41 or half throttle as in an e-32 or idle situation as in an e-33. Sounds like the unit is running ok as of now. Thanks for checking back in and letting us know.

I let it sit for a day with the battery disconnected and the code was gone. I had the shop guys using it for a day while I was working on some Rico lifts. we haven't had it overheat or reset the code. the truck has about 15000 hours on it, so there is probably several worn parts in the peddle.

I would have to say the sensor or related wiring back to the ecu is the problem. An e-33 error code will go away when the engine is cooled down below 220F, and only show before the engine cranks up. once the motor is running and is cooled down, you will again see the the hour meter reading. the code would be "historical" but not "active".
?shorted wire or open circuit from the engine coolant temp sensor?

yes doing the 'pedal dance' can be frustrating at times because it is hard to hit it every time. But if you have identified the overheating issue and repaired it and 'know for a fact' that it is repaired the code generally should clear on it's own. The self diagnostic the truck runs when you turn on the truck would see the condition not present anymore and would turn off the MIL signal. (at least that's how it works in theory according to the manual)

I have seen in some cases where it would not clear using the pedal dance for some strange reason and the laptop or service tool would have to be used to manually clear it.

And of course, if you do not have those opportunities you can always unhook the battery for a period of time. (don't think it would take 4hrs though but to each their own)

Consider this one possibility though, if you have repaired the identified overheating issue and the code still persists even after doing the battery disconnect trick you might consider checking the temp sensor and circuit for faults.

If you did the pedal dance several times and were seriously accurate with the times it says, the code won't clear because the fault has not been repaired. The intervals are critical when using the pedal. If the unit is older, the pedal may have wear and not be fully depressing. I have had to remove the floorplate and depress the actuating rod by hand. Just something to think about.
Just for giggles, you might check the coils. had one giving this code because a coil wasn't seated correctly.

Well, I tried that several time to no avail. Luckily I have the truck in my shop for a few days. So, I'll try the unplugging the battery for 4 hours trick before I tell the boss we have to get the Nissan dealer to clear the code.

you can try the pedal dance and see if that will clear the code

if that does not clear it then you will have to use the service tool to access the ecm and clear it that way

if you are unfamiliar with how to do the pedal dance go to this thread and look for 7777's post, he explains how to do it
h ttp://forkliftaction.com/forum/thread.asp?trid=11073
(remove the space i added in the url at the beginning to make link work)

all that was changed. the fan came apart and destroyed the water pump and radiator. I was coding before all that was changed. How do you go about clearing the code?

Overheat step 2... only idles. Make sure fan belt is tight and radiator isn't clogged or fins bent due to debris being caught in fan. Also check coolant level and waterpump is bled. See if thermostat is not stuck.