Fixing your car doesn't have to be expensive. Thanks to the age of information, anyone can be a "Google Mechanic". While this specific repair may not match your situation, it's the same process. So let's get rid of that annoying orange light.
A word of caution: if you have little or zero experience working on cars or using tools don't do this alone. Find someone who can work along side you to help prevent accidental injury or damage.
Step 1: Buy an OBD Reader.
Really, it's worth it. OBD stands for on board diagnostic. A reader will cost you about $60.00. You can buy one at auto parts stores or even Walmart. It may sound like a lot, but keep in mind, just pulling your car into a mechanic's shop will cost you a minimum of $75.00. That's just to look at it. At least this way you'll always have it and you can help your family and friends later.
Here's the basic principle of how OBD works. Your car has a computer which receives input from different automotive systems. When these systems send the wrong input (something is broken) the computer records the problem and turns the service light on. Plugging in the reader displays the code/s the computer recorded. These codes are generic diagnostic codes and not specific to a model (yes, there are exceptions).
We'll go over how exactly how to use a reader in a later step.
Step 2: Scan for Codes.
It helps if you've paid attention to your car's performance prior to this point. If your vehicle has an emissions problem you may not notice any change in performance. Or, on the other extreme, your car may not even start. Being aware of what symptoms your vehicle has will help you pinpoint the problem. In my case my SUV was having a hard time starting especially after filling the gas tank. This was intermittent for about a month.
Look under the lower edge of your drivers side dash board. You'll find a trapezoid shaped port for the reader. Plug in the reader while the engine and ignition are off. Once connected, turn the key on but leave the engine off (KOEO). Press the scan button and watch the the reader think. It will eventually display codes stored within the computer. Scroll though the codes and write them down. In my case the code is P0496.
Step 3: Search Your Code.
So you have a code, now what? The internet is filled with all kinds of forums and threads. Often the code your vehicle has is a common occurrence with your vehicle. You'll find people have fixed it and written about it. A great website is OBD-codes.com. It will give you a good understanding of what your code/s mean. If your know a thing or two about cars then this will help. If you don't, don't worry. Yes, it helps to know how something works before you fix it but you can get by here.
Search the code along with your vehicle. So here's what I wrote in the search bar. "Buick rendezvous OBD P0496." You might also add your vehicle year but keep this in mind. Vehicle models change year to year but what's under the hood may stay the same for years. If your vehicle is a 2008 and and the post is for your model but 2005 the fix could be the same. I found a post which said it could be the purge valve based off of my symptoms and code.
Step 4: Locate the Part. Remove and Replace.
So now I suspect the purge valve but what is it? What's it look like? Where is it? All these questions have answers you can find by doing an internet search. I found this diagram showing the purge valve. I compared it under the hood and located the part.
Once you know what the part looks like you can order it with confidence. I bought mine at autozone and replaced it in 10 minutes. It was a matter of 1 bolt, 1 hose, 1 electrical connector, and $24.00.
Step 5: Erase the Code.
Now that the part is changed, plug the reader back in. Press and hold the erase button. When the screen changes press the button again to confirm. The code is gone now and your check engine light should be off. This is assuming you have no other codes.
Important: if you're fixing a problem to pass a smog check, drive your vehicle for a day before taking it for testing. The technician can tell if you recently (within 50 miles or so) deleted the code. He will collect his $24.95 and tell you to come back again. If your check engine light is on when you show up, it's also an automatic paid fail. So make sure it's off before inspection.