Just got a new (used) truck. Dealer says the check engine light stays on because of a after-market locking gas cap. He resets it and away I go. Twenty minutes later, it comes on again and I ignore it for a week. I go in to have some keys made ($150 for two keys, chip needed for anti-theft program). I also replaced the locking cap ($20) with a factory cap. Light goes off for a couple of days and then it appears again. Dealer wants to charge $85 to do a diagnostic test.

I have had friends who have their light on for years without any problem. Is this just a gimmick to get you to bring your rig in and get it checked out all the time? What is the worst thing that can happen by ignoring it?

It seems to me that some times we try to idiot proof things to the point that it makes things worse.

Any suggestions for this situation?

my suggestion is to get it checked out......at least find out what the code indicates is wrong. Then you can decide whether or not to do anything more.

It means you got chumped. Sorry to have to say it.

You bought a worn out POS that's going to cost you more in monthly maintenance than it will in payments.

It means there is an issue with the powertrain, because if it was just a stupid gas cap, the problem would be gone.

It means it's a booger on your finger and you need to wipe it off ASAP.

Unless it's covered under warranty, do NOT take a used car to a dealer for repair or maintenance

You will get HOSED. Like getting charged $50 for soiling an oil rag. No joke.

Get rid of that thing.

I did the run around with my local Ford dealer with my '06 F-250 Powerstroke. I finally cornered the service manager after the 2nd catastrophic breakdown in 2 weeks and after 30 minutes of bugging him he finally nervously whispered to me that I had 4 months of warranty left to get rid of the thing.
Find an independent mechanic you trust at least on a business level and do your changes and tune-ups through him. You will save thousands.

Another thing about small town dealerships: They have you over a barrel and they know it. Olympia's like that. All Star knows damn well that locals have to drive 40 miles before you find another dealership and they treat you accordingly. I don't even shop for cars locally anymore, but drive to Tacoma, Seattle, or Bellevue.

Good luck.

In many ways, yes, it's a way for a dealership to build revenue, but, I would also say get this sorted out because there are certain emissions issues that may need to be addressed to get your rig running tip top. One example is your o2 sensors. When these things go south your check engine light will come on to let you know and this is something you'll want to know as you fuel mileage will go to the crapper.
If the check engine light ever flashes or blinks that means you need to address the issue immediately as it may be related to mechanical failure.

Disconnect neg battery cable for 10 minutes. Sometimes that can reset CEL.

1.) Go to Shucks and borrow their code reader and pull the code(s) your self and look them up on the internet.

2.) Buy a Toyota.

Get Jesse

Unplug the battery for 15 minutes. It might reset. If it comes back on, pull the code at Schucks.

While there is a pretty good chance it's the same error code you don't know for sure. If you want to spend the $85 to find out I'd spend it on your own code reader. If not I believe you can have Schucks check the codes for free.

Check engine lights are not a 'gimmick' its not some big dealership conspiracy, it means there is an emissions related problem. Could be a missfire, evap leak (gas cap, which sounds like you bought one), air fule ratio issue etc. Like others have said, go to schucks, have them pull the code for free, and google the code(s) or post it up here and go from there. Disconnecting your battery will not make a problem go away, it does 'reset'your ecu, but if you truly have a problem your cel will come back on, let us know what code you have....

We don't have a Shucks in town but Auto Zone is comparable. They hooked it up to the hand-held gadget and apparently there may be a potential vapor leak in the fuel system. Attendant says to me it is nothing serious but I ask how would you fix it. Probably need to check the hoses and associated lines, worst case drop the tank and inspect it. Then basically replace the part where the leak is.

Thanks for comments guys.

On our trip to BC last fall the light came on right before going through Prince George. Pulled into the dealer, replaced the air filter with a stock one rather than an upgraded filter and that did the trick.

Everyone that owns a newer vehicle should own a Diagnostic Reader. They aren't that much money and they are very handy. As mentioned before, you read the codes and look them up on the internet. Usually it is a sensor that can be replaced fairly easily and they save you a ton of money in the long run.

Codes can also be erased by removing the negative battery cable for about 10 minutes. Since the code comes on and goes off intermitantly, it could be anything and without pulling the codes you won't know where to start. Very often a light that goes on and off indicates a misfire condition and a simple set of spark plugs will solve the problem.

K&N are a big problem, if it has to much oil it will get on the on the MAF, and the MAF won't read right.

Iwant2fish.......check your pm's

You asked some parts monkey how to fix it.

Well you didn't list the code or the vehicle, but it sound like you have a EVAP leak, could be a number of things. But most places with run a smoke test to find the leak, most of the time they are fairly simple issues. But I have a feeling that maybe it isn't so simple, since they didn't fix it in the first place.

Was this a used car dealer or a new car dealer?

I remove and clean my MAF sensor twice a year.

Just after the air filter, sometimes attched to the air box.

Be very careful cleaning it, they're real delicate. Don't touch the element itself, spray the sh!t out of it with special MAF cleaner fluid. Make sure to remove the Neg battery terminal before doing the work. After you're done cleaning it, reconnect the battery terminal and the computer will reset and adjust accordingly. You might also wan't to clean your IAC valve while your there. pm if interested.

I asked the part salesman how it could/would be fixed...just like I asked a bunch of guys on a fishing board what it means. Doesn't mean I'm going to do what anybody says, just gathering information on the subject.

I specifically left out the make and model because then you get a dozen guys questioning your purchase. But if you must know, it was a 2002 Dodge Quad Cab 1500 4x4 with 58,000 miles and it was bought from a used dealer after looking for about 6 months for the features and price I wanted.