Have you checked the hydraulic oil level? Mine will shut down if it has a low oil level. I don't know if that's because the charge pressure drops or because there's a manometer there checking suction pressures as well... but check the oil first.
I can't see why changing the oil filter will improve anything as it's a return filter and should not in any way effect the charge pressure.
I'd have to do a bunch of research to tell you where those sensers are located because I've never had to dig that deep into the problem although mine does sometime set the charge light partially alight... indicating a partial connection somewhere inthe circuit... either a bad sensor or a bare wire somewhere.