The oil pressure could be dropping. Or, the sending unit could be going bad or have loose wiring. Check the wiring and the sending unit. It will take an oil pressure gauge to check that the pressure is correct.
The check engine light stays on when the computer detects an emissions related failure.
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
The sensor may be defective/broken. I would have that checked or replaced.
with scan tool but to keep it from coming back on you must first fix the problem that the truck has.
The light comes on when the computer detects an electrical failure. Have the system diagnosed by a trained technician. The airbag system is not for the diy'r.
Trouble code P0401 means:Exhaust gas recirculation-insufficient flow detected
A flashing check engine light is an indication of an engine misfire.
Whatever component that it drives is probably locking up.
Have vehicle scanned to determine the problem
Have vehicle scanned to determine problem
Because your bonnet's open!
The cycle switch not engaging the Compressors clutch