How Your Check Engine Light Works

Have you ever had an experience like this in Sacramento California? You drive through the one of those automatic car washes. When you get to the end, where the dryer is blowing, your check engine light started flashing!

You fear the worst, but within a block or two, the light stopped flashing, but stayed on. By the next day, the light was off.

You wonder; “What was going on?” Well, it’s actually a good lesson in how the Check Engine light works.
Your air intake system has a sensor that measures how much air is coming through it. When you went under the high-speed dryer, all that air was blasting past the sensor. Your engine computer was saying, there shouldn’t be that much air when the engine is just idling. Something’s wrong. Whatever’s wrong could cause some serious engine damage.

Warning, warning! It flashes the check engine light, to alert you to take immediate action.
It stopped flashing because once you were out from under the dryer, the airflow returned to normal. Now the engine control computer says the danger is past, but I’m still concerned, I’ll keep this light on for now.
Then the Check Engine Light goes off in a day or two.

The condition never did recur, so the computer says whatever it was, it’s gone now. The danger is past, I’ll turn that light off.

Now a flashing check engine light is serious. You need to get it into our Sacramento California shop as soon as possible. But if it stops flashing, so you have time to see if the problem will clear itself or if you need to get it checked. How does the computer know when to clear itself?

Think of it this way. The engine control computer is the brain that can make adjustments to manage the engine. Things like alter the air to fuel mix, spark advance, and so on. The computer relies on a series of sensors to get the information it needs to make decisions on what to do.

The computer knows what readings are in a normal range for various conditions. Get out of range, and it logs a trouble code and lights up the check engine warning.

The computer will then try to make adjustments if it can. If the computer can’t compensate for the problem, the check engine light stays on.

Read more at http://halsautocare.autotipsvideo.com/2012/07/20/how-your-check-engine-light-works/