P0128 Trouble Code

P0128 = Coolant Thermostat Temperature Below Regulating Temperature

Meaning Of P0128 :

P0128 code in a car's onboard diagnostics system typically indicates an issue with the engine coolant temperature. It often means that the engine is not reaching its optimal temperature within a specified time frame.

Engine control module tracks how long it takes for the engine of a vehicle to reach and maintain the correct operating temperature. This timeframe depends on other facts, such as ambient temperature. So the powertrain control module orders the fuel system to enter a done where readings from the oxygen sensors are used to maintain the efficient air to fuel ratio.

Reasons Of P0128

There are four main reasons of P0128 and your car's thermostat might fail:

Overheating: The thermostat detects the heat of the engine, and uses the heat to open and close a valve. The components within a thermostat are only designed to handle operating temperatures, so when the temperature climbs too high, it'll cause the thermostat to fail.

Contaminated coolant: Sludge can build up in coolant, and can get inside the thermostat. This can restrict the efficacy of flow, or prevent coolant flowing through the thermostat. This means the thermostat won't get an accurate reading, and can lead to your engine overheating or overcooling.

Manufactury defects: Like most other car parts, thermostats are mass produced in factories. Sometimes, thermostats slip through the inspection stage with minor defects which can lead to thermostat failure.

Time: Thermostats are constantly being heated and cooled, and after a while, the internal components wear out. It's a slow process, but the temperature at which the thermostat will open climbs higher and higher, until one day your engine overheats.

How To Fix P0128 Trouble Code ?

Use an OBD-II scanner to check for errors. If there are any other codes other than P0128, resolve them first. After that the code indicates that thermostat is not working well.Visually inspect the coolant reservoir and coolant level. Sometimes a low level of fluid or a coolant leak can cause a P0128 error code. Check if the coolant is on optimal levels, and when was it changed last time Check the coolant temperature sensor. For this, you will need to switch the multimeter to resistance testing. The resistance value should change with the temperature. If the readings are the same, then you should inspect the wiring of the sensor or the sensor itself Inspect the thermostat. The P0128 diagnostic trouble code is often a result of a stuck engine coolant thermostat. Check the coolant hose and the temperature of the coolant flowing through it. Be careful when doing this to avoid burning. If the radiator hose takes more than 5 minutes to heat up, the thermostat is constantly open.

Driving with a failed thermostat can damage your engine. A high flow thermostat is ideal for high-performance vehicles, for towing, or any instance where additional loads are placed on the engine.

P0128 Symptoms

P0128 Repair Cost

P0128 code causes 3 different problems on parts: main reason thermostat, coolant temperature sensor and top off coolant. If you replace all the parts it will cost around $350 - $550.
If you need to change them one by one it will cost.

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