The function of automotive environmental sensors
The automotive environmental temperature sensor is a key component that enables the vehicle to sense the external temperature. Its main function is to detect the ambient temperature outside the vehicle and transmit this information to the vehicle's electronic control unit (ECU) to support the intelligent operation of multiple systems.
Main functions
Precise control of the air conditioning system: The sensor continuously monitors the outside temperature, and the ECU automatically adjusts the cooling or heating intensity of the air conditioner based on the temperature difference between inside and outside the vehicle. For example, in hot summer, the ECU will increase the working frequency of the air conditioning compressor to quickly cool down; in cold winter, it will optimize the output of the heating system to ensure comfort inside the vehicle.
Optimize engine management: In low-temperature environments, the ECU increases the fuel injection volume based on the environmental temperature signal, helping the engine start smoothly and reach the working temperature quickly, reducing wear; in high-temperature environments, it adjusts the rotational speed of the cooling fan and the opening degree of the thermostat to enhance heat dissipation, ensuring the stable operation of the engine and improving fuel economy.
Assist the battery management system: For electric vehicles, the environmental temperature data is used to adjust the charging and discharging strategies of the battery and control the cooling or heating systems of the battery to prevent performance degradation or damage of the battery in extreme temperatures, thereby extending the lifespan and improving safety.
Enhance driving safety: Some advanced systems can combine environmental temperature data to determine if the road is icy and trigger anti-skid control or warnings in advance, assisting drivers in dealing with adverse road conditions.
Provide environmental data support: It provides real-time external temperature information to the vehicle's computer systems, navigation systems, etc., supporting the realization of more intelligent functions.
Installation and working principle
Installation location: It is usually installed on the front bumper bracket or in front of the water tank to ensure direct contact with the airflow, avoiding direct sunlight or interference from rain, to ensure measurement accuracy.
Working principle: The core component is the NTC (negative temperature coefficient) thermistor, whose resistance value decreases as the temperature rises and increases as the temperature drops. The sensor converts the resistance change into an electrical signal, which is processed by the ECU and used for system regulation.
If this sensor fails, it may cause the air conditioning to fail to adjust intelligently, difficulty in starting the engine, abnormal cooling system, and even false display of the water temperature fault light. Therefore, regular inspection and replacement with original factory parts are crucial.
Common faults of automotive environmental sensors usually refer to abnormal sensors used by the vehicle to sense the external environment (such as temperature, humidity, light, atmospheric pressure, rainfall, obstacles, etc.), resulting in the failure of related systems (such as automatic air conditioning, automatic headlights, windshield wipers, adaptive cruise control, automatic parking, etc.) to work properly. These faults can be caused by various factors. The following is a comprehensive analysis based on the latest publicly available information:
Main fault causes
Pollution and carbon deposits coverage: Environmental sensors (such as intake pressure sensors, air quality sensors) are exposed to the engine compartment or outside for a long time and are prone to be covered by dust, oil, and exhaust particles, causing the sensing surface to be distorted and the signal output to be incorrect. For example, the nitrogen oxide sensor of a diesel vehicle may fail due to clogging with exhaust particles.
Extreme environmental influence: Vehicles are often exposed to high temperatures, low temperatures, high humidity, or dusty environments, which accelerate the aging of sensor components or cause performance degradation. High temperatures may cause internal components to expand and deform, while low temperatures may make electronic components react slowly; in case of water immersion, if the sensor interface is not waterproof, it may cause a short circuit.
Line and connection problems: The wiring of the sensor may be damaged due to long-term high temperatures, vibration, aging insulation layer, or oxidation and loosening of the plug, resulting in signal transmission interruption or instability. These faults account for approximately 40% of sensor failures and are often manifested as intermittent activation of the fault light. Physical damage and vibration: Environmental sensors (such as radars and ultrasonic sensors) installed on the bumper, chassis, etc. are prone to internal structure loosening, shell cracking or displacement due to minor collisions, road bumps or intense vibrations, which can affect the detection accuracy.
Electromagnetic interference: High-power audio systems and LED lights installed on the vehicle (non-original equipment) may generate electromagnetic interference, affecting the stability of sensor signals.
Service life expiration: Some environmental sensors (such as the built-in battery of tire pressure monitoring sensors) have a designed lifespan (approximately 5-7 years). Using them beyond the expiration period may result in signal drift or delay even if they are not completely failed.
Common fault manifestations
The automatic air conditioning cannot automatically adjust according to the outside temperature
The automatic headlights do not light up or keep shining in the dusk or in tunnels
The windshield wipers start incorrectly when there is no rain or do not work when it rains
The adaptive cruise or automatic emergency braking system frequently misfires or fails
The OBD diagnostic instrument reads fault codes related to environmental sensors (such as P0106, P0110, etc.)
Solutions
Read the fault codes first: Use the OBD diagnostic instrument to read the specific fault codes to accurately locate the faulty sensor.
Check the wiring and connectors: Check if the sensor wiring is damaged, the connectors are oxidized or loose. Do not disassemble them by yourself.
Clean the sensing area: Use a dedicated cleaner on the sensors that can be cleaned (such as intake pressure sensors) and avoid rinsing with water.
Replace expired components: If the sensor has been used beyond the recommended lifespan (such as oxygen sensors after 6-80,000 kilometers), it is recommended to replace it directly.
Professional inspection: For complex sensors such as radars and cameras, it is necessary to go to a professional repair shop for calibration or replacement.
During daily maintenance, avoid frequent water immersion, regularly clean the front area of the vehicle, use qualified fuel and engine oil, which can effectively reduce the failure rate of environmental sensors.
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