Temp Gauge not reading

[CGERD]

Hey everyone, new to this forum and hoping to find an answer to my issue. I have a 2015 Tahoe LT with the 5.3 L engine. Here's the history...Several months ago the temp gauge stopped reading and fans stayed on 5 min after shutdown. Did the normal first step and changed the temp sensor. That worked for 3-4 months and then it started having the same issue. It was very intermittent for several months, wouldn't work for a day or two and then would be fine for a week/month... Now, it's not intermittent, so I changed the thermostat and the temp sensor again, filled the coolant and ran for about 25 minutes to burb any air. The heater blew hot air, but the lower hose never warmed up. I used NAPA parts and I believe they are OEM. Also used a 210 degree therm.

I did not disconnect the battery. Not sure if that makes a difference.

Any thoughts on what might be causing this? My only thought is that I didn't let the engine get hot enough to open the therm and circulate coolant. Not sure if that's accurate or matters, but it's the only thing I can think of.

Thanks for any help.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

It sounds to me like there is still air in the cooling system. Folks will chime on the recommended air burping procedure. @Doubeleive @OR VietVet @swathdiver

 

[jaxscuby]

oh joy..samething happened to my 2016..
I have an older obdII reader and clear the code.

25 minutes should have been long enough to get to operating temps.
During colder months..down here in north florida the check engine light for coolant temperature was more often than
the warmer months.

and now..knock on wood hasn't happened for the past 2 months..
replaced the coolant temp sensor with aftermarket & GM one.
and thermostat.

currently have the gm temp sensor installed.

napa parts are not oem..oem cost more that napa..just saying..
of course unless the box or bag had a gm part number tag or sticker..

 

[OR VietVet]

Welcome to the forum from Oregon.

Attach a live data capable scanner and compare. And to be sure, the engine is not overheating, it is the temp gauge not working?

 

[CGERD]

It doesn't seem to be overheating. I'm not sure how to tell how hot it is though. I'm just handy enough to fix the straightforward stuff. Diagnostics isn't my strong suit.

And when you say, "Attach a live data capable scanner and compare." are you referring to pulling a P code? It did pull a P0128 code prior to me replacing the components. I haven't rechecked yet, I just did the repairs yesterday.

 

[OR VietVet]

You are talking about a code reader only. I am talking about a scanner like Foxwell NT301 that will allow you to SEE what is happening and yes, it will pull codes too.

Amazon.com

 

[Doubeleive]

I am not clear on what the "current" issue is?
works but lower hose is not warming up?
in that case go drive it a couple miles like you are in the indy 500, or getting chased by the cops because you robbed a bank or you are chasing a guy that just r*ped your daughter
do several wide open throttles and get up as much speed as you reasonably can without getting a ticket or in a accident.
either it will act up and get hot or it will work fine and push any bubbles out.
if it seems fine then pull over check re-check the coolant level
note the thermostat reading it should be reading normal as well.

 

[OR VietVet]

I am not clear on what the "current" issue is?
works but lower hose is not warming up?
in that case go drive it a couple miles like you are in the indy 500, or getting chased by the cops because you robbed a bank or you are chasing a guy that just r*ped your daughter
do several wide open throttles and get up as much speed as you reasonably can without getting a ticket or in a accident.
either it will act up and get hot or it will work fine and push any bubbles out.
if it seems fine then pull over check re-check the coolant level
note the thermostat reading it should be reading normal as well.

"Drive it like you stole it", in other words!

 

[Doubeleive]

"Drive it like you stole it", in other words!

if I stole something I am going to drive normal so I don't get pulled over lol