There are a variety of reasons that the check engine light comes on. In cars after 1996, and a select few before, OBDII is the system that checks and finds "problems" that set the light off.

OBDII stands for On Board Diagnostic 2(II)

In most cases, it is something to do with the emission controls that sets the indicator to "ON". Yes, this can be an open gas cap, or it can be a loose connection. Quite often, when doing something as simple as checking the oil, or tranny fluid, changing an air filter, or even a tune up, it is very easy to accidentally pull loose an electrical fitting. Once the car is running, and goes a period of time with no response to the computers queries for information from that sensor, a code is set, and the light goes on.

If the light does come on, but your car does not seem to be behaving poorly, you should have a little time to find the problem. However, if your car is behaving poorly, or barely running, the problem is usually serious, and should be attended to right away!

That being said, if your check engine light comes on, you can take a few simple steps to eliminate any obvious culprits.

A: Check to make sure your gas cap is on!

B: Open the hood, and look for any loose, or disconnected wires, and see if you can plug them back in. Be observant, most cars do NOT have the same kind of connections near each other, so it is hard to plug 2 wrong connectors together!

C: In the dark, whether at night or in your garage(beware exhaust fumes!), with the hood up and the engine running, check along the plug wires for small blue sparks, this will also cause the light to come on! The wires losing spark causes the engine not to burn all the gas in the affected cylinder, leaving to much oxygen, and sets an O2 sensor code.

D: After these simple checks, many of the larger auto parts stores will"pull" the code for you, and occasionally can recommend the fix, for free! Even if you cannot affect the repair yourself, you are now a little better armed when dealing with a mechanic, or the dealer.

E: If you are a do it yourselfer, you can purchase an OBDII scanner for less than $100. The hookup for the scanner is usually under the dash, near the fuse box, on the drivers side of your car.These scanners can also delete the code, but that will not help you pass an inspection if the problem is not fixed first, but does allow you to tell if you fixed all that was wrong. Consult your manual with the scanner for more details.

F: On many Chrysler products, you can turn the key to the "on" position, then off, and back and forth 3 times, leaving the key in the on position. The check engine light will then flash the code to you. Google this for more in depth detail, and how to interpret the flashes.

As you see, this doesn't have to be an insurmountable problem. With a little time and foreknowledge, the check engine light can help you find and fix a problem before it escalates.

Good luck!

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