Check Engine Light

Okay. You went to the car wash and while the car was under the dryer, the check engine light started flashing. Panic! What did you just do? Something is seriously wrong with the car! You head for the nearest service station, but on the way, the check engine light stops flashing, and just glows red. Hmm. Maybe things aren’t as bad as they seem. You decide to wait until payday to take your car in to get serviced. In the meantime, the check engine light goes off. What? You decide the light must be faulty, or that when it comes on it doesn’t mean anything, or that it’s just in your car as some sort of scam to get you to pay for unnecessary repairs. You’re glad you didn’t take your car to the repair shop and resolve to ignore that engine light in the future.

Whoa! Let’s look at what really happened. Your car was under a hot air dryer. Your air intake sensor measured a lot of hot air running through the engine. It sent its report to the engine computer, where a warning was triggered: there shouldn’t be that much airflow when the engine is idling. This is a serious problem that could cause permanent engine damage. Warning! The check engine light starts flashing, letting you know you need to take immediate action to prevent that damage.

You drive out from under the dryer, and the air intake sensor sends a new message to the computer. The computer realizes that everything is normal and tells the check engine light to stop flashing. The vehicle doesn’t need immediate attention; but there was a problem, and it should be checked out. After a few days the computer senses that the problem is gone, so it turns off the warning light.

You may think this story illustrates the uselessness of a check engine light, but you should remember that a computer can’t think for itself, it can only follow its programming. It doesn’t know the difference between a hot air dryer and a serious malfunction in your engine. That doesn’t make it useless. It just means you have to be the smart one. Being smart doesn’t mean ignoring your check engine light or disconnecting it. It lets you know when something is wrong, and you can prevent a lot of damage to your vehicle by paying proper attention to it.

Your engine computer is constantly collecting data about what is going on inside your engine. It knows what parameters are normal, and when a reading may indicate a problem. It uses the check engine light to let you know when something isn’t right. It then stores a code in its memory that a service technician can retrieve that indicates which reading was abnormal.

Our technicians at Wade's Auto Service uses this code as a starting place to find out what’s wrong with your vehicle. It’s like going to the doctor with a fever. The fever is the reading that is abnormal—your temperature is too high—but the doctor still has to figure out what’s causing it. It’s probably an infection, but what kind? Sinus infection?

Appendicitis? Flu? The problems and their solutions are quite different. But a fever also tells a doctor what’s NOT wrong with you. Fevers don’t accompany stress headaches, ulcers or arthritis, so there’s no sense in testing for those conditions.

Your service technician at Wade's Auto Service responds to a trouble code in your vehicle’s computer in the same way. The code doesn’t say exactly what’s wrong, but it does give the technician a good indication of where to start looking—and where he/she doesn’t need to look.

Now, you wouldn’t consider diagnosing yourself with a serious medical problem good medical advice—unless you’re a doctor. So you shouldn’t consider trying to diagnose your vehicle’s troubles by yourself good auto advice—unless you’re a trained mechanic. Wade's Auto Service in Farmington, MO is the shop to bring it to. 

There are cheap scanners available on the market and some auto parts stores offer to read trouble codes from your engine computer for you, but these are really not good alternatives to taking your vehicle to a qualified service center. Your engine’s computer has both short-term and long-term memory, and there are some codes that are specific to a particular make and model of vehicle. Cheap scanners can’t read an engine computer’s long-term memory nor can they interpret manufacturer-specific codes. That’s why a good auto service center like Wade's Auto Service spends a lot of money on high-end diagnostic tools.

It’s as if you had a choice between a doctor who had a tongue depressor and a thermometer and one who had all the latest medical equipment on hand. Honestly, which would you choose?

Getting your codes read at the auto parts store isn’t really a money-saver, either, unless you’re a trained mechanic. You’ll end up with a code that tells you a symptom. What usually happens next is that the parts store sells you something that directly relates to the symptom. It may or may not fix the problem. It’s actually cheaper to just go to the service center and get things fixed right the first time. Remember, a fever can indicate a sinus infection or appendicitis. Aspirin is okay for that sinus infection, but it won’t help your appendicitis. And do you really want to wait around to see if the aspirin helps when you might have appendicitis?

Part of good car care is knowing where you can get a problem fixed, and fixed right. Preventive maintenance goes a long way to keeping you out of the repair shop, but eventually, we will all have a problem that needs fixing. Let’s do it right the first time. In the long run, it’s actually the less expensive choice.