nicely put edwardt
but i thought the caterpillar p5000 was the diesel engine that powered the Red October ;o)
hehe

ok, enough kidding around now :o)
yes that code may be persistant until cleared and can only be cleared when the problem is resolved. If the problem is not resolved then the code will return and stay there till once again cleared. via diagnoser or the pedal dance, your choice.

But i will reitterate that the relays have been a problem in these trucks since thier introduction into the market and only in the past year or 3 have they updated them with a better one that does not fail as quickly. (the green ones).
If that truck is a newer one with a serial number after AT351xxxxx then it most likely has the new ones in it.