2001 Buick Regal P0128 Code: What Does It Mean and Should I Replace the Thermostat?
My 2001 Buick Regal recently triggered the Service Engine light, which came on after short daily drives to and from work. The warning light turned off a few days ago, but today I was diagnosed with P0128 — indicating that the engine coolant temperature is below the expected level for proper thermostat operation. The coolant level is currently at normal levels, and the vehicle runs smoothly under regular conditions. Given that the check engine light has already turned off, should I still replace the thermostat? Or could there be another cause, such as air in the cooling system or low coolant circulation? Any insights would be greatly appreciated.
The P0128 code may point to a faulty thermostat, but it's also possible that air is trapped in the cooling system or that coolant levels are actually low. Before replacing the thermostat, ensure the radiator and hoses are properly bled and check for any signs of leaks or air pockets.