What is the reason for the coolant alarm?
3 Answers
The reason for the coolant alarm is: the coolant level is below the electrode, causing the circuit to fail to conduct. The vehicle's computer uses this signal to determine that the antifreeze is insufficient. The functions of coolant are: 1. To provide anti-corrosion protection for the engine's cooling system; 2. To prevent the engine water from boiling when the temperature reaches 100 degrees Celsius; 3. To prevent the formation of scale, avoiding reduced heat dissipation efficiency of the radiator; 4. To ensure the engine operates normally under low temperatures. The method for replacing coolant is: 1. Open the vehicle's engine hood, and the coolant reservoir can be seen in the upper right corner; 2. Open the coolant drain plug under the radiator to drain the old coolant; 3. Add new coolant, tighten the cap, and the coolant replacement is complete.
Once when I was driving home, the coolant warning light suddenly came on, which scared me so much that I immediately pulled over. After checking, I found the coolant level was very low—it turned out there was a tiny crack at the radiator connection that was slowly leaking. Coolant warnings usually indicate insufficient fluid levels, triggering the warning system when the engine temperature gets too high. There are many possible causes: leaks in the cooling system, often due to aging and cracked hoses, failed water pump seals, or corrosion holes in the radiator, especially in older vehicles with worn components; or natural evaporation of coolant that hasn’t been replenished in time; sensors might also give false alarms, though this is rare. Ignoring it can lead to engine overheating damage, such as cylinder deformation or cylinder head warping, significantly increasing repair costs. For safety, as soon as the warning light comes on, you should stop to check the coolant level, top it up with coolant or distilled water as a temporary fix, and then get it repaired as soon as possible. Regularly monitoring engine bay temperature and unusual smells while driving can help prevent issues in advance.
The coolant warning light coming on mostly indicates a system malfunction, and I happen to have studied cars for many years. Common causes include insufficient coolant levels, where the fluid drops below the min line and triggers the alarm—this often stems from leaks such as radiator cracks, loose hose connections, or water pump leaks, with vehicle vibrations exacerbating the issue. A faulty thermostat stuck in the closed position can also block circulation, causing the coolant temperature to rise and trigger the alarm. A broken coolant sensor may falsely report abnormal temperatures, while air bubbles in the system can disrupt pressure and cause false alarms. Long-term neglect of coolant maintenance leads to fluid degradation, corroding system components and increasing leak risks. When the warning light activates, immediately check the coolant reservoir level and look for signs of leakage to prevent engine overheating and core damage. Minor issues may only require coolant replacement or leak repairs, but severe faults may necessitate fixing the water pump or radiator. Regular maintenance by car owners can minimize such troubles.
