C15 high oil pressure

hey guys I just brought a 07 Kenworth 404 with a c15 engine. 1.1m kms with a bearing roll done less than 100,000ks ago. The oil pressure gauge wasn’t working at time of purchase. Anyway I sent it in to an auto elec three days ago to get it fixed because my check engine light and stop engine light would flash then stay on solid during first startup then disappear once warmed up.( I did a fault flash test which came back with codes for low oil pressure 46 and low coolant level 62 ) So they replaced the oil pressure sensor and coolant sensor. My oil pressure gauge then showed just a touch over 100kpa idle and 500kpa at 1500rpm and over..... then I left it sit for a couple days and started it today and it was idling at 500kpa then crept up to 600kpa after ten minutes or so, I then revved it a bit for a while at 1500rpm and after a while the pressure came down to around 300kpa at idle but sat at 600kpa at 1500rpm. So I held it at 1500rpm for about a minute to see if pressure would drop more then the check engine light and stop engine light started flashing a lot so I shut it down. Done another flash code test which came back with 46 62 12 8. This has made me really anxious. I don’t know wether it’s slectrical or something serious.....I also tried a new gauge and that read exactly the same. So oil pressure sensor and gauge are new. Haven’t done a pressure test straight to the block yet and the oil looks pretty old.

 

Thanks for the replies guys. I spoke to a CAT mechanic who said it should be idling around 110 kpa and rev around 300kpa.... my gauge Max’s out at 600kpa so I’m assuming it shouldn’t reach that max limit also there’s the check engine and stop engine light coming on again....