5 Things Your Check Engine Light is Trying to Tell You

Is there anything that can strike more fear in your heart than seeing that blazing Check Engine light – besides a semi driving straight for you? OK, maybe red lights flashing in your rear-view mirror, but you get the idea.

What does the Check Engine light mean? You shut off the radio, yell at the kids to be quiet, and perhaps for the first time in months, you are really listening to how the car sounds and feels.

Should you keep driving it? Should you see your mechanic ASAP? How many people do you know who drive with that light on for months? We bet quite a few.

In this article, we are going to talk about that dreaded Check Engine light and what you should do (or not do) if it should turn on. We will also discuss the most common codes (reasons) that make this happen.

What is it?

In a nutshell, this light is part of your car’s computerized diagnostic system. The computer monitors the performance of certain items, such as spark plugs or the oxygen sensor. When it detects that some part is either failing or it has failed completely, the computers try to alert you with that Check Engine light.

Can I Drive with the Check Engine Light On?

In some cases, yes. If everything on the car sounds normal and the car is running normally, you can drive it. However, we wouldn’t drive it for too long (such as months at a time). The light may have come on simply because the oxygen sensor needs to be cleaned. You can keep driving your car, but you certainly aren’t going to pass your next emissions test.

Some models now have a way of trying to tell you that Check Engine light is serious by having the light blink. You need to have it looked at . . .yesterday. In some cases, the Check Engine light comes on exactly when the part breaks – not giving you much notice in advance. In short, if the Check Engine light starts flashing, do your best to get it to a repair shop ASAP. Or, at least pullover and stop the first chance you have so you can call roadside assistance or a tow truck.

If the Check Engine Light Stays Steady and Doesn’t Blink- Check the Following

Unless the car starts running poorly, feels as if it will stall, or if the gauges show that the car is overheating, check the following to see if any of these simple fixes will make the light turn off.

1. Check the Gas Cap

No, we aren’t kidding. The gas cap keeps gas fumes from polluting the atmosphere and is a part of your EVAP system (sometimes called the smog system). Something as simple as a loose or missing gas cap can make this light on your dash turn on. Tighten the gas cap until it clicks a few times. If the gas cap is missing, replacements are easy to find. If the cap no longer tightens, buy a new one.

A loose, missing, or broken gas cap is probably the #1 reason the Check Engine light has come on.

2. Reduce Your Speed

This will reduce the amount of pressure on the motor and can help buy some time until you can get to your local mechanic.

3. See Your Mechanic Soon

Don’t think that putting a piece of black electrical tape over the light solves the problem (yes, people have done this). Some people say that there is nothing wrong with the car and that Check Engine lights are simply ways for dealers and mechanics to make money, but this is 100% false.

The 5 Most Common Codes Responsible for That Annoying Check Engine Light

Beside the fact that this light on your dash is glaring at you while you are driving, some people or parts stores use code readers that allow them to access the vehicles codes. These codes give the mechanic a place to look, but they don’t always spell things out clearly. For example, a code might indicate the fuel system and nothing more. Where do you start? You don’t want to start replacing parts until the light goes off! This is where a mechanics knowledge and expertise will save you a ton of money and headaches.

Don’t forget that some manufacturers have their own proprietary codes and what one code means for one make of vehicle may not be the same for another make.

The following are the 5 most common codes that turn on the Check Engine light.

1. P0171-P0175- Oxygen Sensor

This is a very common car problem, right after the loose gas cap. The O2, or oxygen sensor, measures the oxygen in the exhaust. This sensor frequently becomes dirty or plugged, or it eventually fails.

2. P0300-P0305-Engine Misfire

Here is an example of what we were talking about above. An engine misfire can come from any one of a dozen parts, everything from a bad spark plug to a weak ignition coil. A trained mechanic will find the problem quickly through a few tests.

3. P0411, P0440, P0446, and P0455- Evap System

We talked earlier in this article about the Evaporative system, commonly called the EVAP system. This is part of the smog control. This code could mean that loose gas cap we referred to, a charcoal canister, a purge valve, or just a plain old vacuum hose.

4. P0401- EGR Valve

This is also a part of the smog system on your vehicle. The exhaust gas recirculation, or EGR, valve sends a portion of the exhaust back into the motor so it can reburn gas vapors. If you make quiet a few short trips (less than 10 miles), this valve can become clogged.

5. P0420, P0430- Catalytic Converter

This part looks like a muffler and is found between the muffler and the engine itself. The catalytic converter (CAT) uses special metals to catalyze the exhaust gas, changing toxic exhaust gas into less harmful gases. If the CAT begins to fail or if it become clogged, you can overheat. Or, it might refuse to go any faster than 20 or 30 MPH, no matter how hard you press on the pedal.

Remember that these are simply the most common codes. There are dozens of other codes and reasons for the Check Engine light to turn on. So, it is important that you get your vehicle serviced by a trained mechanic as soon as possible.

Don’t waste time and money with those “shade tree” or back alley “mechanics” who simply keep replacing parts until the light goes out. Or worse, still removing the light bulb but charging you for a repair!  Use a repair facility with a good reputation and ASE certified mechanics, like the ones you will find at Hong Kong Auto Service.

Call us today for an appointment or drop by so we can see what codes are stored in your vehicle, so we can tell you what is wrong and repair it ASAP.