Check engine light is on with code P0128, coolant thermostat?

2015 HYUNDAI SONATA

40,000 MILES • 2.4L • 4 CYL • 4WD • AUTOMATIC

ELIZABETHBROWN87

MEMBER
1 POST
FOLLOW

Hi, my check engine light is on and I’m getting a P0128 error code. Coolant level is fine. My temperature gauge is reading normally. Starting cold and then heating up in 5-7 minutes of driving to sit in the middle of the gauge. No rapid fluctuations or signs of overheating. A/C and Heat are working normally. Does my thermostat need to be replaced or could it be something else? Thank you!

Sep 26, 2022 at 11:53 AM

Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.

STRAILER

AUTOMOTIVE REPAIR CONTRIBUTOR
54,178 POSTS

Since the engine is heating up quickly, I would say the engine coolant temperature sensor needs to be replaced. Start by draining the coolant, here is a guide to help you through the steps and the instructions and location of the sensor and the images below.

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Check out the images (below). Please let us know what happens. Clear the codes once the job is complete.

Images (Click to enlarge)

Sep 26, 2022 at 4:22 PM