Engine Light On

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bevo_daddy

500+ Posts
What's the best way to see what is wrong with your car? I know you can get a diagnostics check for like ~$60 just to find out what is wrong.

Is there an easier/ cheaper way?
 
Autozone will plug in a diagnostic reader into your car for free. It plugs into my truck underneath the steering wheel.
 
Autozone will plug in their diagnostic tool, get a code, and tell you the code meaning, all for free ...

Murphy's law says that fixing the cause will be beyond your expertise and will require the services of a qualified mechanic.

Bottom line ... pay for it and get it fixed right.
 
This happened to my ex-wife once, and it was simply because she didn't have her gas cap tightened all the way. I'm serious.
 
The gas cap thing is the cause for 100% of my check engine light warnings (dealer finally told me). Something about air getting into the system and screwing up readings. It goes away after several starts.
 
AutoZone will read the code for free, but that doesn't always give you the answer to why you have that code.
Sometimes it is a simple answer, like the code than can be caused by a loose or missing gas cap.
But that code doesn't actually mean the gas cap is loose. It means that a sensor in the gas tank sensed that pressure is not being maintained in the gas tank. It can be caused by a loose gas cap, or by a leak in the evaporative emissions recovery system, which has hoses, charcoal canister, and solenoids that allow the gas fumes to be routed into the engine and burned in there after you start the car. You check the gas cap first, because that is easy. But it may need a checkout of that whole system, which is not quick or easy.
Also, the person at Autozone often disconnects the code reader from the car while it is running, or erases the code.
This removes the stored data from the computer which can be used by a technician to find hard to trace problems, at the least, and at the worst, can ruin communication for future scanners without replacing some of the electronic parts in the car-GM vehicles are succeptible to this happening, apparently.
Don't ever let the Autozone person removed the code reader plug while the car is running.
There are dozens of possible codes, and only some point right to the problem. Some only tell you some generic information like "random cylinder misfire," or fuel system lean.
Any code can be caused by what the computer thinks is wrong, like oxygen sensor on bank 1, but it can also be caused by a wiring problem or a computer problem.
So you can replace the oxygen sensor, but it doesn't always fix the problem or make the code go away.
You have to decide whether to try a replacement part, or pay to have a checkout of that system from a shop, which should follow the factory recommended flowchart for checking that system to eliminate other possibilities.
Sometimes paying for a proper diagnostic check is the cheaper way to go, because you haven't replaced some expensive parts the car did not need.
Sometimes replacing the part the code suggests is bad is the cheaper way to go, and is all the car needs.
 
Again, knowing what a code is does not mean you know what part to replace.
And I don't think there will be any record of the code remaining after you erase it, and the data that the ECM used to light up the code will be gone. There is information stored in there about when the code happened, how many times it happened, what the temperature was, what the RPM was, etc.
 
Yeah I went to Autozone yesterday and had the code read. It said EVAP Cooler or something like that and he said it could be anything from the gas cap to some hoses in the engine. He erased the code and told me to get it checked out if it comes on again.

Im happy now until it comes back on, I just hate the engine light
 
Evaporative emissions system.
It will take two "drive cycles" to come back. First, you remove and reinstall the gas cap, and make sure it clicks a few times.
Then if the code returns, and it is the same code, get a new gas cap, preferrably a factory gas cap.
Have the code erased, then see if the code returns yet again. If it returns, take it to a competent shop to diagnose.
Oh yeah, you could look under the hood on your air cleaner assembly to see if a rubber hose is unhooked from there from when Quick Lube took your air filter assembly apart to sell you an unneeded air filter, and they always leave the hose off, which gives you the evap code the second time you drive the car afterwards. WalMart does this all the time. So much so that you would have to wonder if it is incompetence, or intentional.
 
I'll take your word for it, as we don't work on GM. May get a good new scanner that will check all models, though, which has an extensive training class-so I might know about that in the near future.
 
The software I have lets me see all diagnostics of a GM vehicle (while running) on my laptop. You can see if there are any history codes as well as the cycles left before you get "system ready" in order to pass inspection.
 
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