What could be wrong with the car when the "check engine" light is on?

Could be nothing serious, could be very serious indeed.

Check engine lights come on when the vehicles computer "senses" a situation where a vehicle sensors are out of value.

This could be anything from low oil pressure, high oil pressure to an incorrect fuel air mixture. There are literally hundreds of potential reasons. some vehicles in even turn on the check engine light when you're due for an oil change

Most parts stores have a small computer that will interface with the cpu in the car to retrieve the codes or the cause of that light coming on. One word of caution, some immoral part store workers and some dubious mechanics will use their code scanner and then over emphasize the problem in order to sell more parts or charge you for unneeded work.

it is a double edged sword in some respects. most part stores and some mechanics will not charge you to retrieve the cosea from your vehicles cpu. but you must still be cautious so that you're not taking advantage of.

here is something that you can do at home by yourself free of charge. that is if you're comfortable with some basic tools and work skills.

if you remove the battery cables from the battery the vehicle computer will clear its memory. when you reattach the battery cables and start your car the check engine light should have gone off. now you can drive your car to see if the check engine light issue reoccurs.

if there is something obviously wrong with your vehicle you should go ahead and seek the services of a certified professional mechanic. otherwise you may try resetting the computer as described earlier. I hope this helps

As the others say, the key to knowing what it is complaining about is to have the codes read. Country Boy has a good warning about getting the codes read at a retail outlet - although the codes are accurate they are very easily misinterpreted. My favorite example is the several codes that mention a heated oxygen sensor. The sensor itself is almost never responsible for any of those codes appearing.

The light does not care at all about your oil pressure but there are literally hundreds of complaints it may have. As long as the light does not flash you can continue to drive it. If it flashes, reduce power and get off the road when you get a chance, much like you would if the engine overheats.

The most common causes of the light coming on in a car your age are a loose or leaking gas cap or blockage of the EGR system with carbon from the exhaust. There are plenty of other suspects, though. Please ask again when you know the code(s) responsible; they will start with P, and usually P0, like P0302 (cylinder 2 misfire). Otherwise, Country Boy's advice about the dealer is good. The codes can mislead mechanics unfamiliar with your Grand Marquis.

It began again in the 50's when manufactures made up our minds that individuals were too dumb to read gauges, and began striking oil strain and generator fool lights on dashes. Back then, it used to be easy to figure out the concern though. Now, the check engine gentle comes on, and who is aware of what it probably? It can be quite often a sensor that's out of spec, but until you've a plug in software to see what the onboard computer says, you're pressured to take it again to the dealer and get charged a butt load for them to do it and repair the trouble. I hate new cars.

In 1997 Fords should be able to store their codes in the on-board computer.

A word to the wise: You can have the code read free at Advance Auto or Auto Zone. The results will get you exactly no-where. Each of these stores crappy "tea-leaf" readers will spit out a code which can have up to 20 specific cause possibilities.

A Ford garage on the other-hand has up-dated expensive diagnostic equipment which will tell you the EXACT cause of the code.

Take it to an autozone or o'reilly's, they can communicate with computer and see where the problem is. It's most likely either a spark plug not firing every time, or it's just an oxygen sensor. The ck eng light is from the car's computer sensing a bad reading in one of the sensors, it should be checked because it makes the computer use a default reading but it reduces your fuel milage

The check engine is telling you that you may have a trouble code being pulled by your cars computer. You need to have it checked out by a trained techinican with the proper tools for it. As long as you are not having any problems that are showing you can drive the car with no problems.

you will have to have the car scanned for trouble codes. when one is tripped, it turns on the c.e.l. good luck. most chain stores will scan it. write down the codes and come back with them.

CHECK ENGINE....CAN COME ON FOR ANY ONE OF MANY THINGS, NOT POSSIBLE TO TELL WITHOUT DOING A COMPUTER SCAN,,,,,,,MANY AUTO PARTS STORES WILL READ IT AND TELL YOU THE PROBLEM FOR FREE