Fault phenomenon
    The customer read the car after the idling normal, but driving a few kilometers of engine idling rose to 1940r / min, high; hot car after the fire and then very difficult. In addition, fuel consumption is also higher than before. The car mileage of 210,000 km.
    Fault diagnosis analysis and processing
    With the gold Pentium public / Audi - Chinese 1552 car computer decoder to retrieve the fault code, coolant temperature sensor G62 open / short circuit SP. Because it is accidental soft failure cleared, but after the flame to see the 1552 to pick up the fault code and the above fault code. During the road test, the temperature of the coolant temperature sensor G62 was found to be 96 ° C at the time of the vehicle, and then gradually decreased, 96 ° C → 89 ° C → 45 ° C → 27 ° C → 0 ° C → -17 ° C → -28 ° C. When the water temperature dropped to 27 ℃ when the throttle released idling began to rise, gradually to 1940r / min or so, at this time 1552 show water temperature -28 ℃. It seems the coolant temperature sensor is indeed a fault, after stopping, even hit the 6,7 under the car. In order to verify the coolant temperature sensor is good or bad, unplugged its two-pin plug, the results suddenly launched, 1552 show water temperature 95.2 ℃. But incredible is the water temperature table has been showing about 90 ℃. Replace the coolant temperature sensor, the failure to lift the cold car hot car hit the car. Note that it is important to loosen the lid of the swollen kettle before releasing the coolant temperature sensor to relieve the cooling system to prevent boiling water from burning out.
    Failure analysis
    Santana Gli's coolant temperature sensor is a two-pin NIC (negative temperature coefficient thermistor), the lower the temperature, the greater the resistance. It converts the temperature of the coolant into a different electrical signal to the engine control unit ECU to control the amount of ignition, ignition timing and idling speed. However, when the coolant temperature sensor is damaged, the engine ECU will activate the water temperature preset value of 95.2 ° C instead of the engine coolant temperature until the fault is removed. After removing the coolant temperature sensor plug, the coolant temperature is 95.2 ° C Constant.
    to sum up
    The temperature of the coolant is to correct the amount of fuel injection that is the size of the size, to reach -28 ℃, the engine ECU sure to inject more fuel injection mixture, idling rise, fuel consumption is not surprising. Hot car just after the flame, the coolant temperature sensor to the engine control unit ECU temperature is still negative, the engine control unit ECU is bound to tell the injector more fuel injection, fueling too much to plug the spark plug, hot car and then car It is very difficult.
    For the detection of the coolant temperature sensor, we can put it in the cold liquid heating, the resistance between the two pins to determine its good or bad. In addition, the coolant temperature sensor damage can cause the engine to start difficult, idle instability, easy to flame and other failures.