What are the warning signs of a coolant temperature sensor failure?
2 Answers
Signs of a faulty car coolant temperature sensor: 1. Difficulty starting the car When the coolant temperature sensor fails, it often displays the temperature signal of a hot engine during cold starts. The ECU cannot receive the signal to provide a rich air-fuel mixture, and can only supply the engine with a lean mixture suitable for a hot engine, making it difficult to start the engine when cold; 2. Short circuit in the coolant temperature sensor or wiring causes the temperature gauge needle to point directly to the highest position; if the coolant temperature sensor or wiring is short-circuited, the temperature gauge needle will not move at all; contamination on the coolant temperature sensor can lead to inaccurate temperature readings; 3. Affects the EGR valve. The function of the coolant temperature sensor is to convert the coolant temperature into an electrical signal, which is input to the ECU to: adjust the fuel injection quantity; increase fuel injection during low temperatures; adjust the ignition timing; advance the ignition timing during low temperatures and retard it during high temperatures to prevent knocking; affect the idle control valve; during low temperatures, the ECU controls the idle control valve based on the coolant temperature sensor signal to increase the idle speed.
There are quite a few warning signs before a coolant temperature sensor fails. I've experienced this situation myself – while driving, the temperature gauge needle would fluctuate erratically, sometimes showing low temperature even though the engine felt extremely hot to the touch. This was accompanied by particularly difficult cold starts, requiring multiple ignition attempts before the engine would fire up. Later, I noticed the engine was running unevenly too, with severe shaking at idle that felt almost like a misfire. Fuel consumption also skyrocketed – I was burning half a tank more than usual even on highway drives. The cooling fan operated unpredictably, sometimes spinning wildly and other times not running at all. The most alarming was when the coolant temperature warning light started flashing. All these symptoms indicated potential sensor aging or internal short-circuiting. It's crucial to immediately check for corrosion or oxidation at electrical connection points. Prolonged neglect could lead to engine overheating, cylinder scoring, or even complete engine failure – repairs for which are extremely costly. As preventive maintenance, I regularly check coolant levels and keep the system clean to minimize such failures.
