Intermitting temp sensor

Wvguy2026 · February 8

Hello, just purchased a 19 Silverado 4.3l I’ve been chasing my tail looking for a fix. I am showing the 2 following codes.
P0117 and P0119 (see screenshots). I am lost. I have replaced the coolant temp sensor, reset the codes. Drove and it came right back (the Service engine light).

i have cleaned the connection with contact spray, connector looks fine too.
checked battery cables they are tight.
Cooling fans are stuck on 90% of the time as well. Temp gauge bounces between cold and normal operating temp. It never exceeds the normal temp.
any suggestions would be welcome.
I also meant to add it starts really rough and or stutters.
Please and thank you

Edited February 8 by Wvguy2026
Add text

davester · February 9

It's possible the new sensor you put in, is also bad. Or there is a wiring or connector problem somewhere. Or the ecm is bad (unlikely, but possible).

alldata.com has wiring diagrams, connector pinouts and vehicle-specific diagnostic procedures, that you can use to find what is causing those codes.

I would guess a wire is broken somewhere, I would probably start with closely examining the wires as they enter the connector at the sensor, to see if the insulation is bulging or damaged, and then move on to end-to-end testing of the wires involved with that sensor.

johnnyquick · February 11

Be sure that you got all the air out when you replaced the sensor, check the voltage at the sensor both when cold and once it warms up and as stated above check for bad wiring, corroded connections etc.

GMCustomerService · February 19

We're regretful to hear you're having engine light concerns with your Silverado and would like to investigate this further with you. Please send us an email to [email protected]. Be sure to include your Username and Forum/Thread in the subject line with additional details. We look forward to your email.

newdude · February 19

On 2/8/2026 at 6:34 PM, Wvguy2026 said:

Hello, just purchased a 19 Silverado 4.3l I’ve been chasing my tail looking for a fix. I am showing the 2 following codes.
P0117 and P0119 (see screenshots). I am lost. I have replaced the coolant temp sensor, reset the codes. Drove and it came right back (the Service engine light).

i have cleaned the connection with contact spray, connector looks fine too.
checked battery cables they are tight.
Cooling fans are stuck on 90% of the time as well. Temp gauge bounces between cold and normal operating temp. It never exceeds the normal temp.
any suggestions would be welcome.
I also meant to add it starts really rough and or stutters.
Please and thank you

Find the broken wire perhaps?

21-NA-149 1..32

Read condition 2 and cause 2 in that TSB and see if there is any broken wiring. Coolant temp wiring is a blue wire which is signal to the ECM and the black with yellow stripe wire is the low reference line.

Wvguy2026 · February 19

4 hours ago, GMCustomerService said:

We're regretful to hear you're having engine light concerns with your Silverado and would like to investigate this further with you. Please send us an email to [email protected]. Be sure to include your Username and Forum/Thread in the subject line with additional details. We look forward to your email.

Currently, my truck is at a Chevrolet dealership certified service. They have replaced the wiring and the pigtail along with the temp sensor. They have told me that the entire wiring harness may need replaced under the hood.