Greetings all and thanks
98 4.6 Expy, Drives great well maintained. Driving home the Temp gauges runs up to max along with the oil light coming on. Truck does not seem to be running hot. Oil level and condition is right where it needs to be. I have read about both the Cyl head sensor and maybe cooling sensor causing issue's. Maybe even oil press sensor?

Just bought a new actron reader. no codes thrown. Does display coolant temp though. 189-195 driving temps

What do you think??

 

The temp is normal.
A sensor must be bad.

 

Stranger things has happened! After this little hiccup, I decided to replace the coolant and thermostat. (records show being overdue) Drained and replaced coolant along with thermostat. Filled system, ran checked for leaks etc. Next morning after arriving to work noticed coolant leaking from underneath tank. Drove home that nite and gauges pegged again however PCM through a P1299 code and truck went into limp home mode. Attempting to "burp" system again and replacing rad cap. Borrowed a block tester to see about gases in the coolant. Test turned fluid into a Green but not "yellow"state. so not sure about the gas test myself.
Two kids in college makes a tight budget so fingers are crossed.
Any comments are welcome!

 

I have the same problem you had. I replaced t-stat, radiator, coolant temp sending unit. Heater core. No result. Have you figured out the problem with yours??? Need help.

 

My water temperature pegged, oil light also came on, but came back down to normal before I had driven half a mile, head gaskets fixed mine. Exhaust gases were getting into the coolant. Hopefully yours is something else. Let us know how it turns out.
Good luck.

 

how did you tell it was the head gaskets? And also how can you tell about the exhaust gas in the coolant? Will it change the color or something?

 

test charging system too, I have seen a bad alternator cause gauges to act funny. Dash may have to be removed and re-soldered if the problem is not in the engine or sensors?