I’ve been working on cars for a little bit now (recently picked up this hobby) and my dad’s 2016 Chevy Suburban (close to 200,000 miles) has had one specific code come up several times over the years: P0128. Every time it has come up, it’s just been a temperature sensor replacement. The code just came up again, and this will be the 4th time the sensor has had to be replaced. I’m curious if this is a common issue with Chevy.
P0128 on those is 99% of the time the thermostat. Quit throwing sensors at it; obviously, it wasn’t the sensor after the second time the light went on.
My dad always brought it to a dealership, and that’s always what they replaced. Wasn’t sure why after the second time. Makes sense that it’s not the sensor.
I will never understand why people repeatedly replace a part. It’s not the sensor; you probably need a thermostat. Assuming coolant level is normal, P0128 is always a thermostat, never a sensor.
It’s the thermostat.
Like others have said, it’s the thermostat. The thermostat in that model year Suburban is a simple wax bulb unit. You can test it in a pot of boiling water; if it doesn’t open and close smoothly or doesn’t seal soundly when closed, toss it. They’re cheap enough; just put a new one in regardless.