2001-5.3-Check Engine Light Codes

[Pointer 21]

I've got a 2001 Chevrolet 5.3 throwing the following codes:

P0118-"Replace Engine Coolant Temperature Sensor" as per AutoZone
I had a coolant reservoir essentially blow up on me while the truck was sitting idle with my dog in the A/C while I was in home depot. Long story short-I was out of town, had a small shop install a new
reservoir and never looked backed.

-I'm assuming this would be the reason for this code and it should be a plug and play with a new sensor? Fairly easily install?

I believe the next two codes are/have been my pain for many years....Here we go:

P0405-EGR Position Sensor Circuit Low Voltage
P1404-EGR Closed Position Performance

-When this was my daily driver I used to go to Autozone and get the "Guaranteed to Pass" Emissions fluid for the gas tank (broke college kid). It would turn off the check engine light, pass emissions and I do the dance the next year. The vehicle barley is driven these days and I'm considering selling it (It runs well with only 165k miles on it, hard to just give it away seeing as how she likely has some life).

It has dual pipes and a lift.

Any thoughts on what these codes are telling us and what I can do to fix it properly?

 

[JackFox]

With the least amount of assumptions, I would say both parts have failed. The EGR sounds like it could be dirty and not seating al;l the way, and it's position is reporting back to the computer correctly (by not assuming there is a wire problem, Occam's razor) the temp sensor should never read that close to 5 colts. Engine would have to be 300 degrees! This is not more resistance, it's less. Assuming no wire issure, it's a bad thermister. replace them both and you should be fine! SHotgun diagnostics baby.... at least we have some automotive knowledge and logic to guide us. which is why shotgun diagnostics work 90% of the time. ALso, replace your left valve cover. You just KNOW it's burning oil because of it! If not, it will!