Beware of summer: Silent temperature sensor failures are more common at the station

Subtle temperature deviations affect ignition, engine consumption and durability, without turning on the injection light

São Paulo, December 2025 - High temperatures in summer and intense use of air conditioning lead vehicle engines to operate under greater thermal load. Specific sensors play a strategic and silent role in protecting the mechanical assembly, with the mission of maintaining engine operation within an ideal temperature range.

Coolant temperature sensor (ECT ou CTS) is vital to engine efficiency. It provides data to the control unit (ECU) to adjust the air/fuel mixture and ignition advance, avoiding detonation problems. While the thermostatic valve, water pump and electric fan physically control fluid circulation and heat dissipation, The sensor monitors the temperature of the coolant and the efficiency of the entire heat exchange process. In modern vehicles, This management goes beyond the engine and the system also regulates the oil temperature in automatic transmissions and CVTs, preventing overheating of the entire drivetrain. Correct maintenance of the cooling system involves changing the fluid as recommended by the manufacturer and checking the efficiency of thermal exchanges through the system..

Cooling System Problems, also affect the thermal exchange of spark plugs, may cause damage to the engine. To ensure car efficiency in the hottest months of the year, The NAT, brand of Niterra, Japanese multinational also responsible for NGK, guides you on how to identify subtle coolant temperature sensor faults, even without the injection light coming on. Check it out below.

1. Comparison of reading with cold engine: with the engine completely cold, the temperature displayed on the scanner must be very close to the room temperature. Significant differences indicate possible signal drift or loss of sensor accuracy, even without a fault recorded on the on-board computer.
2. Heating curve monitoring: after the match, the temperature rise must occur progressively and continuously. Slow responses, Oscillations or stabilization at values ​​inconsistent with actual engine heating suggest sensor degradation or thermal transfer failures.
3. Comparison with external measurement and system behavior: the scanner reading must be compared with measurements carried out by an infrared thermometer on metallic points close to the sensor. Persistent deviations, associated with irregular activation of the electric fan, increased fuel consumption or excessive heating in urban use, indicate faults that do not necessarily trigger the injection light.

“Not all ECT sensor failures result in the injection light coming on.. Slight signal deviations or slow thermal responses can cause the system to operate outside of the ideal range, causing continuous thermal stress that accelerates engine oil degradation, especially during the summer. Even without registered fault codes, These anomalies can be identified through a careful technical diagnosis.”, explains Hiromori Mori, Niterra Technical Assistance Consultant.

Quality sensors make a difference in summer

As temperatures rise in summer, the vehicle's cooling system begins to operate under greater stress, which makes the use of original quality sensors strategic. Precise sensors guarantee the correct reading of the engine’s thermal conditions, enabling proper system adjustments and contributing to component longevity and compliance with emission limits, even in heat peaks.

Although outside temperature has limited impact on ignition cables and coils, Failures in the cooling system can cause overheating located under the hood, accelerating the wear of these components and putting the engine itself at risk. That is why, preventive review of the system and the use of reliable sensors are decisive to maintain performance, the durability and safety of the mechanical assembly during the hottest periods of the year.

Niterra do Brasil, through its NGK brands, ignition components specialist and NTK automotive components specialist, offers a range of solutions for the automotive repair market.