cpu fan fail sun 450

hello everyone
i have a sunfire450 sparc
recently the cpu fan 2 fail
so i try to with the stop-a setenv env-monitor disabled
this works only once
after that when it boot it give the error messages

fan fail 0xdf, retries 3
cpu fan2 fail
fan fail system shutdown

i dont know how to make it boot again
plz help

pd: sorry for my bad english

Replace the fan?