If you have access to lifter it a diy job
buy a gear box service kit , which is a sump gasket , a filter and the oil
make sure it is cold before working on it
drain the oil and then remove the gear box sump
once the sump is off ,remove the oil pick up filter , 5 bolts
Make sure you clean the sump before refitting , top up oil and it should be fine
filters break down and pull in on themselves which causes the problem
to reset th3 code , pull the ecu fuse , wait 5min then replace
job done