Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
Qu'est-ce que cela signifie ?
Code P0128 indicates the engine coolant temperature has not reached the thermostat's regulating temperature within a specified time after starting.
Avertissement : Ce code de diagnostic fait partie du système OBD2 standard et peut s'appliquer aux modèles Mercedes-benz Glc fabriqués de 1996 à 2026. Cependant, veuillez noter que la présence de ce code dépend de la configuration exacte du moteur, des options et de l'année de production.
Causes courantes
Thermostat défectueux ou bloqué
Capteur de température du liquide de refroidissement (ECT) défectueux
Fuite de liquide de refroidissement ou niveau bas
Symptômes à surveiller
- Le voyant moteur est allumé
- Consommation de carburant accrue
- Le moteur cale quand il est froid
- Voyant de température de liquide de refroidissement allumé
Comment Diagnostiquer
Solutions Courantes
Replace the Engine Coolant Thermostat: This is the most frequent cause of a P0128 code. The thermostat is likely stuck in the open position, allowing coolant to continuously circulate through the radiator, preventing the engine from reaching its optimal operating temperature. Ensure to use an OEM or high-quality aftermarket thermostat with the correct temperature rating for your specific vehicle.
Replace the Engine Coolant Temperature (ECT) Sensor: If the ECT sensor is providing an inaccurate, consistently low temperature reading to the Powertrain Control Module (PCM), the PCM will incorrectly believe the engine is too cold and trigger P0128, even if the engine is at proper operating temperature. This is less common than a faulty thermostat but a definite possibility.
Flush and Refill Cooling System: If the coolant level was low, or the coolant is old, contaminated, or has an incorrect mix ratio, a proper flush and refill with the correct type and concentration of coolant can resolve issues related to poor heat transfer or air pockets within the system. Ensure proper bleeding of air from the system after refilling.