What is the principle of the coolant temperature sensor?

[VonLondon]

The principle of the coolant temperature sensor is as follows: 1. The coolant temperature sensor is a negative temperature coefficient (NTC) thermistor, with a semiconductor thermistor inside. As the temperature increases, the resistance value decreases. 2. The DME calculates the resistance by measuring its voltage value, thereby determining the coolant temperature. The coolant temperature sensor has two pins: PIN1 is the signal line, and PIN2 is the ground line. The higher the coolant temperature, the lower the resistance; the lower the coolant temperature, the higher the resistance. 3. When the coolant temperature sensor fails, there will be a fault memory, and the engine cannot accurately calculate the fuel injection amount. The engine may shake or emit black smoke, and the engine's power and fuel economy will be affected.

[CamilleFitz]

The working principle of the coolant temperature sensor is actually quite simple. It's a thermistor installed in the engine cooling system, responsible for measuring the coolant temperature. When the temperature changes, the resistance value inside the sensor changes accordingly - for example, resistance decreases when temperature rises and increases when temperature drops. The vehicle's computer, called the ECU, reads this change and converts it into a temperature signal. The ECU then adjusts the engine's operation based on this information, such as injecting more fuel during cold starts to warm up the engine faster, and reducing fuel injection when hot to prevent overheating. This component is quite important as it optimizes fuel efficiency and reduces emissions. If the sensor malfunctions due to issues like loose connections or internal faults, the engine may experience shaking, sluggish acceleration, or the coolant temperature warning light may illuminate. It's best to have a technician check the coolant level and sensor condition during every maintenance service.

[GavinMarie]

As someone who's been driving for years, the coolant temperature sensor is essentially the engine's thermometer. It operates on the thermistor principle - when coolant temperature fluctuates, the sensor's resistance changes accordingly, allowing the ECU to read real-time temperatures. The computer uses this data to control fuel injection, fan operation, and other functions to prevent engine overheating or freezing. It works tirelessly behind the scenes during normal driving. If it fails, you might experience hard starts, increased fuel consumption, or warning lights on the dashboard. For basic maintenance, check for loose wiring connections, but leave deeper repairs to professional mechanics. These small components play a crucial role in engine longevity and driving safety, even if they seem insignificant during daily use.

[EstherDella]

The principle of the coolant temperature sensor is based on thermistor variation. It is installed on the coolant pipeline, where changes in coolant temperature cause the resistance value to increase or decrease. The ECU reads this signal to obtain engine temperature information. Based on this, the ECU optimizes fuel injection and ignition timing to enhance engine performance. Common faults include sensor aging or wiring issues, which can lead to unstable engine operation. During maintenance, resistance testing or diagnostic tools should be used for inspection. Keeping the sensor clean helps extend its service life.

[Martin]

Once my car had trouble starting when cold, and after inspection, it turned out the coolant temperature sensor was faulty. In principle, it measures temperature using thermosensitive materials: when the coolant is hot, resistance drops; when cold, resistance rises. The signal is sent to the ECU, which controls engine behavior. Normally, the sensor works silently to ensure smooth driving; once it fails, the engine struggles to regulate temperature, potentially leading to overheating or a spike in fuel consumption. I recommend paying attention to dashboard warning lights—don’t wait until the problem worsens like I did. Related components like the radiator should also be regularly maintained to prevent failures.