Skip the auto shop - Our mechanics make house calls

Q: P0128 code, but coolant is full

asked by on

I got this code when I checked the computer on my vehicle: "P0128". I looked up the code and it means "Coolant Temperature Below Thermostat Regulating Temperature". This code showed up about a week ago. I cleared it, and the vehicle actually passed inspection right after.

Later the same day, the Check Engine Light came on again, with the same P0128 code. My coolant level is just fine, so I apparently don't have any leaks. What might be causing the code? Thermostat perhaps?

This is most likely caused by the thermostat partly stuck open. The coolant sensor would need to be tested to make sure it is not bad, though. I would test the thermostat at the housing with a temperature tester, and compare it to the coolant sensor readings.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. P0128 code, but coolant is full

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Check engine light with P1717 error code

The code does pertain to the transmission selector range switch. This switch tells the transmission what gear you are selecting. This code can be induced if the battery voltage got below 11 volts. I would suggest having the code cleared;...

Q: Coolant light is on almost always

If you have the GS model, that means you have the supercharged version of the 3.8L engine. The naturally aspirated 3.8L has problems with the intake gasket leaking, which results in coolant/oil intermix. However, the supercharged version is not as...

Q: Car overheating

An overheating vehicle and leaking fluids can sometimes go hand in hand. The information provided for your Jeep is a bit limited, however I do believe I can point you in the right direction. There can actually be several different...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.