7 Reasons Why the Engine Fault Light Turns On

by MOU YONG HONG on December 01, 2021

Engine failure light is a problem that every car owner cannot ignore, which is directly related to engine life and driving safety. VEP Engine parts sort out the common causes of engine failures, which are usually caused by the following reasons:

1. The quality of gasoline is poor, not up to standard

Most car owners have this experience. Soon after the car is refueled, the engine malfunction light is on on the dashboard of the car; this is generally because poor quality gasoline is added to the non-standard gas station, which causes oil and gas when the engine is working. The mixture is not fully burned and the engine fault light is on. This will not affect driving safety, but will more or less cause damage to the engine. 

2. Oxygen sensor failure

Nowadays, two oxygen sensors are installed in the car, one at the front and one at the front of the three-way catalytic converter. The function of the front oxygen sensor is to detect the air-fuel ratio of the engine under different working conditions, and the ECU computer adjusts the fuel injection quantity and calculates the ignition time according to the signal. The rear is mainly to detect the working of the three-way catalytic converter! So if the oxygen sensor is damaged or the sensor plug is damaged or loose, the mixture will be too thin or too thick, which will cause the fault light to turn on.

In fact, the oxygen sensor is a very durable component, as long as the fuel quality is good, it can be used for 3 years or longer. Therefore, the fault light of the new car is on, you might as well check whether the oxygen sensor plug is loose.

3. Airflow sensor failure

The airflow sensor is also called an airflow meter. It detects the amount of inhaled air and converts it into an electrical signal and transmits it to the electronic control unit ECU. According to the optimal air-fuel ratio, the ECU indirectly determines how much fuel to spray. If the airflow sensor or the circuit fails, the ECU will not get the correct intake signal, and the normal fuel quantity control cannot be carried out. As a result, the mixture is too lean or too rich, and the engine cannot work normally.

Although an abnormal air flow sensor will not cause the engine to fail to start, phenomena such as unstable idling, poor acceleration, backfire in the intake pipe, and black smoke from the exhaust pipe is still very possible.

4. Spark plug carbon deposit

The uneven quality of fuel on the market and the congested urban traffic make car spark plugs prone to carbon deposits. Carbon deposits in spark plugs can lead to poor engine operation, difficulty in starting, unstable idling, poor acceleration, rapid refueling and tempering, excessive exhaust, Abnormal phenomena such as increased fuel consumption.

5. Engine knock

When the engine sucks in the oil and gas mixture, the compression stroke has not reached the expected ignition position, and various factors outside the control cause the oil and gas mixture to self-ignite and burn. At this time, the huge impact force produced by combustion is opposite to the direction of piston movement, causing engine vibration. This phenomenon is called knocking. The performance is that the car is weak and the engine noise is too loud, accompanied by the sound of knocking cylinders in severe cases.

6. The water temperature sensor is damaged

There is a thermistor inside the water temperature sensor. The lower the temperature, the higher the resistance, and the higher the temperature, the lower the resistance. When the engine water temperature is low, the water temperature information input from the water temperature sensor of the water temperature gauge to the ECU makes the air-fuel ratio richer, so that the engine is stable. The operation is not normal. Similarly, if a cold engine message is sent after warming up, the air-fuel ratio will become richer and the engine will not work normally.

7. Engine cylinder is missing

Obviously, the lack of cylinders in the engine will cause the car to consume a lot of fuel, emitting black smoke, the car will not be able to accelerate, the jitter will be serious, the engine noise will also increase, and the vehicle will be easily stalled. The lack of cylinders in the engine mainly comes from the ignition system and fuel supply system, including carbon deposits on the spark plugs and damage to the high-pressure fuel pump.

In either case, the engine fault light is on, you need to use a computer tester to diagnose, if it is a fake fault code, just clear it out. If there is a real fault, it needs to be checked and repaired according to the fault code. If only the engine fault light is on, the car is driving normally without obvious abnormalities, you can continue driving, and have time to check it at a professional repair shop; if the water temperature is too high or the oil pressure warning light is also on, you can clearly feel that the fault exists. Turn off the fire in time and call for rescue immediately.


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