04 3 sensors need to be replaced where are they

hi i helping a friend dont have a service book for this van
its a 04 2 wheel drive i thinking venture van
the code scanner said

Oil pressure switch
Crank Sensor Block
Crank Sensor Pully or something like that

where are they and is it hard to get remove etc and i thought engins only had one crank sensor?

What were the P codes?

oh i dont know off hand now
i only wrote down

that it was oil pressure switch and said the 2 Krank sensors is there more then one of each of these on these new engines ill have to rescan it then

Sensor in side of block between firewall and engine (mid block), one up top behind/ under power steering pump, and a third IIRC in the front down low behind harmonic balancer........ So what were the codes.......

Oil Level switch is in the bottom of the pan, IDK of an oil pressure switch, again, what are the codes......

Get the codes pulled and let us know, it may not be bad sensors......

Were the intake gaskets or any work recently done? IIRC the sensor wires on one are easy to nick/ cut when replacing the intake gaskets...

IF it actually runs the 7x sensor on the firewall side of the block is good (it connects to the Ignition Control Module and allows it to know when to fire.....