Symptom hub
Engine Runs Too Cool: Thermostat, Sensor, or False-Cold Data?
If the engine never seems to reach normal temperature, fuel economy drops, or the heat stays weak, this is not the same branch as real overheating. The useful split is between a thermostat stuck open, low coolant or flow imbalance, and a temperature sensor or wiring path that reports the engine colder than it really is.
Likely related codes
Start your diagnostic path here
P0115 — Engine Coolant Temperature Circuit Malfunction P0116 — Engine Coolant Temperature Circuit Range/Performance P0117 — Engine Coolant Temperature Circuit Low Input P0118 — Engine Coolant Temperature Circuit High Input P0119 — Engine Coolant Temperature Circuit Intermittent P0125 — Insufficient Coolant Temperature for Closed Loop Fuel Control P0128 — Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) P0126 — Insufficient Coolant Temperature for Stable Operation P011A — Engine Coolant Temperature Sensor 1/2 Correlation P2183 — Engine Coolant Temperature Sensor 2 Circuit Range/Performance P2184 — Engine Coolant Temperature Sensor 2 Circuit Low P2185 — Engine Coolant Temperature Sensor 2 Circuit High