I have a 1998 nissan maxima. The temperature gauge started off by jumping around from cool (normal) to hot. If I tapped the dashboard the gauge would jump from normal to hot. Now the gauge will gradually rise to hot within a few minutes of driving. 10- 15 minutes. I have not seen other signs of over heating, or at least nothing a novice would see. The upper radiator hose gets hot quickly, the lower hose close to radiator will stay cool and the part of the hose attacked to thermostats gets warm. The radiator buffers were worn with caused the radiator to move around, so I replaced those. I have replaced the Temperature switch and sensor as well as radiator fan. I have a new thermostat at the ready. When I plug in my code reader it shows a coolant temperature of 190* all while gauge is at top line (overheating). I have a stored code, P0400 and a pending code P0105. The engine seems to idle and run fine, not loud or anything i would say would be an issue. The only issue i see is the temperature gauge. Although I am not sure if the entire lower radiator hose should be hot after driving. Can I trust the code reader, is my car really not overheating and the gauge is just broken? Is it safe to drive? I finally got my pre covid job back and really need to know my car is good to go to start on Monday and I can't afford a mechanic until paychecks start coming back in. Any advice would be greatly, GREATLY, appreciated.