My younger sister has a 1996 Ford escort that has a check engine light on for quite a while, can anyone tell me what could be the problem. My knowledge is limited to earlier models without electronics controling everything. A list of possilibities would help.

-- mitch hearn (moopups@citlink.net), January 19, 2002

Answers

I know nothing of Fords but check engine light came on my Chevy a few times, running great, no problems, finally took it to the shop...put on a new gas cap...something about the vacuum??? This really made no sense to me but the light doesn't come on anymore.

-- DW (djwallace@sotc.net), January 19, 2002.

For 12 dollars maybe just hook up a manual pressure gage to the oil sending unit. At least she would know the oil pressure was ok. I work on the old stuff too, can't figure out the new stuff.

-- Cindy in KY (solidrockranch@msn.com), January 19, 2002.

Please don't spend any money yet..Do this: Stop the car, get out and walk around to the gas cap. Unscrew gas cap, and screw it back on. The check engine light will go out after a few miles or even sooner. Something to do with epa emission controls. My car lets me know if the gas cap is loose and fumes are escaping. This fixes it everytime!

-- Susan in Northern Michigan (cobwoman@yahoo.com), January 20, 2002.

Mitch, another thought...When it is really wet out or I go through a big puddle, my check engine light always comes on. Once I drive a while and get whatever really warmed and dryed out (sometimes for many many miles), the check engine light goes back out. I chaulk it up to "quirks".

-- Susan in Northern Michigan (cobwoman@yahoo.com), January 20, 2002.

96 ford, check engine light CAN BE ANYTHING,, you have to "pull some codes" to tell you what could be wrong,,sensors,, timing a tad off, exhaust,, ect,,ect,ect,, Can be anything,, you can buy a gadet that will pull the codes, or take it somewhere do get it done

-- Stan (sopal@net-port.com), January 20, 2002.

i agree with susan, its your emmisions control, if you dont get it fixed, it will eventualy ruin your engine, (iknow)\ cody

-- cody (urbuste@alltel.net), January 20, 2002.

Being a 96 it is old enough to have passed some kind of mileage milestone. Many vehicles are programed to have the check engine light come on at 60,000(?)miles. Just a way to get you into the shop for a checkup.

Diana

-- Diana (dvance4@juno.com), January 20, 2002.

Stan is correct, it could be anything. You need to take it somewhere where they can read the code and that will tell them why the check engine light is coming on.

-- Anita in NC (anitaholton@mindspring.com), January 20, 2002.

could be the oxgyen (O2) sensor. Cost about 15-20.00 you need a special wrench - 15.00 - to take it off

-- mark (toymeister@hotmail.com), January 20, 2002.

The check engine light goes on whenever the computer is fed a voltage or resistance reading from an injection sensor, temp sensor, o2 sensor, MAP, MAS, Fuel pressure, you name it sensor that is outside operating specs. The most prevalent causes are fuel filter clogs, o2 sensor malfunction, egr clogs, fuel tank vent clogs. There is a way to fool with the ignition switch to get the light to blink in a specific series of long and shorts to tell you what the codes are. The fuel pressure code however will not tell you if it is the filter, the vent, or a rusted line or a bad fuel pump. I don't have the book for the codes on the escort, but it should be available. Alternatively you can spend some dough on getting the computer printout of the codes and their values from the shop.

Oscar

-- Oscar H. Will III (owill@mail.whittier.edu), January 20, 2002.

As said before it could be a number of things, but before you spend any money having it hooked up to a scanner disconnect the battery for 30 minutes and than reconnect and see if the light is still on. If it is a reaccuring problem the light will come back on after a short trip. If it was a temporery problem such as a loose gas cap, water spraying or just a blip in the system the light will stay off.

I hope this info helps. Good Luck!

-- Mark in N.C. Fla. (deadgoatman@webtv.net), January 20, 2002.

O2 sensor most likely your culprit....has you MPG gone down?

-- Sue (sulandherb@aol.com), January 20, 2002.

I actually had an 85 1/2 for a few years. I had an oil pressure indicator go bad on me, and the gas cap as mentioned above.

-- Eric in TN (eric_m_stone@yahoo.com), January 21, 2002.

My husband has a '93 Escort- same problem w/ the check engine light. His has been on constantly, I think, for a few years now. We have never found that tightening the gas cap has ever made a difference. A mechanic did tell him that it's most likely a sensor, we had a diagnostic test done back when it first came on-no luck in them figuring it out. It now has about 115k miles on it, and besides the usual wear and tear replacement, he hasn't noticed anything out of the ordinary. I'll tell him about some of the ideas I saw that the others wrote...I want to say that this 'check engine' light came on around the 60,000mile mark,but I may be way off on that too. Kinda makes you wonder if it IS just to get you back into the shop to spend more $$$........

-- Nancy (heartsathome45@hotmail.com), January 22, 2002.

Shut off the motor and disconnect the battery for ten minutes, then reconnect, this sometimes helps. If it comes back on it needs to be worked on.

-- Scott (scotthom@hotmail.com), January 22, 2002.

Could be virtually anything.

Computers run your cars now. Previous posts are correct in that it will detect some abnormal condition with the sensors and possibly some of the devices the computer activates. It could be due to many things.

1996 cars fall within OBDII specs (onboard diagnostic). As such, small problems or something intermitent is watched by the computer but is not acted upon unless the problem is persistant. If the problem continues the computer finally lights up the MIL (malfunction indicator light) or check engine light.

Although replacing the OX sensor is good to do on high mileage cars, many are replaced needlessly. A scanner will tell you that you may have a bad OX reading. MOST OF THE TIME it is due to some other fault. For example, my wifes car set the MIL and was blowing black smoke. Naturally a scanner said I had a bad OX reading. The dealership wanted to replace the computer and the OX sensor. The trouble was a 50 cent piece of vacuum line that was leaking and playing tricks on the vacuum sensor (MAP sensor). The MAP sensor was telling lies to the computer saying it was reading low vacuum (hey we must be going up a steep hill). So the computer for some weird programming reason ignored the OX sensor and increased injector timing (more fuel).

NEVER disconnect your battery in attempts to make the light go out. The MIL will come back on in a short time anyway. Doing so will result in two things,

1. You will lose the history of what all the problems are (not a biggie as the computer will relearn what is wrong)

2. The computer will have to relearn how to run the engine with the fuel that is in the tank (injector timing, ignition timing, etc...). In the meantime you have to put up with a possibly hard starting car, poor performance, etc...

If you want to fix the problem yourself some outfit markets AutoTap

Autotap is scanner software that runs on your PC. It actually is more powerfull then those expensive scanners you find in dealerships and shops as it has powerfull graphic features that take advantage of your computer monitor to display.

As I charge around in a '90 Olds it is OBD compliant (pre-1995 roughly). For the older cars (OBD) there is DIACOM software. I probably looked silly with my home system in the driveway connected to the car, but it worked.

I have since picked up a cheap laptop on Ebay that will run DIACOM.

Really came in handy for a friends car. It would shake and conk out when you came up to a stop. Everybody (many professionals included) were telling her that it probably was a fuel problem. Seemed to me it was acting like a stick shift and failing to use the clutch.

Sure enough it would only happen when the lock up torque converter was activated. Turned out the computer was ok, it was the lock up solenoid valve not releasing (mechanical problem - not electric). The solution was to deactivate the solenoid vale by killing the power feed to it.

Didn't mean to rattle on like this, but it is easier than you think to be able to troubleshoot powertrains on the new cars, IF you were good at troubleshooting the old ones.

The nicest thing about scanner software that runs on your pc is that you can take a data snapshot of your engine conditions when normal. When you run into problems it provides a standard for comparison to the new data representing a problem.

I'm gonna break this keyboard if I keep this up

Good luck

-- Don Denhardt (desulfator@yahoo.com), January 23, 2002.

Ooops forgot - mileage induced trouble lights have not been used for a long, long, long time. 1980 something and on if the MIL is set there is a problem. It will reduce your ulitimate mileage or can cost you big if you don't get it fixed. Trouble is finding a wrench that is good at troubleshooting.

I used to refer people to the dealerships. They have the factory manuals, factory training, possible previous experience knowledge, etc...

After that child mechanic told the service manager about the computer and OX sensor change needed I have since not referred anyone to a dealership. Better to find an old mechanic that can use a scanner.

-- Don Denhardt (desulfator@yahoo.com), January 23, 2002.

If it is your O2 sensor it costs about $50 for the upstream sensor and about $75 for the downstream sensor...and if anyone knows where I can find schematics on the entire engine w/o buying a $30 chiltons manual please email me!

-- Shane Perry (perry411@comcast.net), April 24, 2002.