Check engine light is different from other warning light on the dashboard such as oil level light or water temperature light.  If check engine light is on, the problem is much more complex. Check engine light is also a common problem.

If check engine light comes on suddenly while driving, can I continue to drive?

This is a very difficult question, the problem of check engine light can be severe or mild. Even no problem also can be detected "false failure", and another phenomenon is that check engine light occasionally is on or off. In fact, this false failure is also very easy to understand, indicates the fuel is not up to fuel standard, or the oil is poor quality. Other problems (such as carbon deposition) caused by insufficient mixture combustion can illuminate engine warning light. Fuse and some of the sensor circuit is under poor contact due to vibration when a car is running, which also lead to check engine light on occasionally.

But more often, check engine light indicates some faults, which need to troubleshoot and fix the problem timely, otherwise it will cause further damage to the engine, or even break down in the road. The best way to solve the problem of the engine light is to read the fault code at the car maintenance services, but for us, sometimes we use the car in a hurry. Obviously the ability to determine whether the car can continue to use or not is very important. Generally, when the engine fault light is on, the car is bound to be accompanied by a series of other symptoms, we can start with the symptoms and then determine whether the car can continue to use.

1. Car shakes and stalls intermittently

Ignition system fault can also cause check engine light, and spark plug or ignition coil failure caused by cylinder misfire to intermittent shake severely. The symptoms are best recognized, but sometimes is not necessarily the spark plug failed, maybe carbon deposition lead to stall. Generally, spark plug cleaning can solve the problem.

2. Oil burning (exhaust blue smoke)

When oil burning is more severe, the exhaust pipe will emit blue smoke, of course, the symptoms can be severe or mild. The symptoms of engine warning light are likely to be accompanied by blue exhaust smoke. The possible causes of sudden engine oil burning include clogged oil sump filters, badly worn piston rings, aging valve seals, and PCV valve failure and so on. PCV valve failure will also cause the car unstable idle speed. If the car has poor acceleration, it may also be due to loose valve closure, result in intake valve leakage. The intake valve failure due to the top bending will cause the intake valve closure is not tight. There was no doubt that the blue smoke from the exhaust pipe indicated that the oil consumption was so severe,  the car would have to be stopped and delivered to car service maintenance in time.

3. Poor acceleration 

Check engine light is on, which is the most fault symptom when accelerating. There are many reasons cars can't accelerate, the car can no longer continue to use, need to detect and repair as soon as possible in this condition. 

Detection

(1) If the fuel pump (filter) is blocked or the fuel pump is broken, but the car continues to use, there is a risk of breaking down halfway.

(2) Clogged oil passage of fuel filter and fuel injector will greatly increase fuel consumption, resulting in weak acceleration and wobble.

(3) Failure of sensors such as oxygen sensor, air flow meter and water temperature sensor will also cause weak acceleration.

4. Unstable engine idle speed

Severe carbon deposit of throttle valve and idle valve will also cause unstable engine idling speed, shaking and have a difficulty starting car. If air filter is too dirty, also will affect the intake of air, resulting in unstable engine idle speed; Some signal sensor faults, such as the front oxygen sensor, air flow meter and other faults will cause the engine air-fuel ratio error, leading to unstable engine idle speed.

5. Car is hard to start

The failure of carbon canister solenoid valve and water temperature sensor idle speed lead to unstable engine idle speed. The failure of carbon canister solenoid valve is easy to cause the hot engine to start.