To actually fix the part once you narrow it down? If you have it in hand.... about 10 minutes if you have to hunt for sockets that fit. Less if you know what it takes.
To figure out when you have 12 codes tripped to run through with diagnostic testing on all of them? 4 hours of diagnostic work at $75 an hour, $85 for the part which by the way, was a blown LB7 take-off because there wasn't one available in the COUNTY and he called a guy he did an engine swap on, who kept the block. This was "Bro-Tier" hookup level in bumf--k Nebraska, for someone he didn't even know and just rolled up into the shop. This wasn't your classic "hmm haww well I dunno" mechanic, this guy was rocking 2 computers, scan tool, probing, checking every.single.connection on the block etc etc... I was there the whole time. Money well spent because honestly I had NO clue what was going on, and there were also other things.. cleaned MAF, couple loose plugs tightened, etc etc.
Money I would rather not have had to spend, but I know that many shops would have taken a couple days as well as once the fault was ID'ed, would have been at a dead end when Napa and any other parts house went "Nope, but we can have it next monday"...