Help Understanding/Solving "Service Engine Soon" Light on 1998 Ford Windstar
April 4, 2007 5:58 AM   Subscribe

What is the best way to resolve problem with "Service Engine Soon" light coming on very intermittently on a 1998 Ford Windstar, 3.8L engine, 67,000 miles?

Car is driven about 5,000 miles per year. Spark plugs and wires have recently been changed. Van runs fine.

Any ideas? Any help is much appreciated.
posted by seinfeld to Travel & Transportation (13 answers total)
That's pretty low mileage for a vehicle of that age, so initially, I'd rule out problems with sensors and EC equipment, and look for more prosaic issues:

1) Gas cap problem, particularly with rubber gasket that maintains positive seal for fuel system.
2) Leaky hoses from Evaporative Emissions Control Canister (located up in the engine compartment).

The best thing to do would be to get a diagnostic readout of the vehicle's Diagnostic Trouble Codes, which Autozone or other auto parts stores will often do for free. They can also check for related factory recalls and service bulletins.
posted by paulsc at 6:10 AM on April 4, 2007

There is a lot of good information here. I was able to fix my Windstar's intermittent light after trying some of the easier things on that page (the final piece of the puzzle was the L-shaped vacuum elbow replacement).
posted by mr_crash_davis at 6:15 AM on April 4, 2007

The best way to resolve the problem is to take the car to a dealer (or independent shop) and have them scan the computer for fault codes, so they can diagnose the problem.
posted by Thorzdad at 6:26 AM on April 4, 2007

Go to AutoZone and they'll read the codes for free. No need to spend $50 or more just to get the diagnostic code and a print out telling you what is wrong with the vehicle. If there is a serious problem (transmission, etc) they may not be able to pull the code, so you will have to go to a dealership and pay them to do the diagnostic.
posted by ganzhimself at 6:41 AM on April 4, 2007

AutoZone might be OK for general codes, but at times you need to 'drill' deeper and then the high price scans are worth the cost.
posted by raildr at 7:00 AM on April 4, 2007

For what it's worth, our Windstar almost always has the engine light on, and our mechanic said it's not really anything worth fixing.

posted by niles at 8:00 AM on April 4, 2007

I agree that you should take the car to AutoZone or whatever similar establishment exists in your area. Generally, they'll scan your codes for free and if nothing else that will at least tell you where to look for the problem. The service engine light was turning on and off intermittently in my '99 Accord, and it turned out to be a minor exhaust problem that could be safely ignored.

One other thing I will say is that if the problem does turn out to be ignorable and you end up driving around with your check engine light on, it'd be a good idea to have your codes scanned again every now and then just to make sure nothing else has gone wrong. The light doesn't change when a second code is set after the first one, so you'd have no indication if a new problem were to arise.
posted by Vorteks at 8:14 AM on April 4, 2007

A piece of electricians tape over the offendin light is what my mechanic recommended.
posted by jaysus chris at 8:32 AM on April 4, 2007

If the code is something that isn't serious you should be able to reset the computer by disconnecting your battery for 10 minutes or so. I believe there is an issue where that light comes on in Windstars and there is nothing wrong. If the code keeps coming back the dealer should be able to flash the PCM with new software.
posted by ganzhimself at 9:37 AM on April 4, 2007

On a Windstar, be very careful.

The O2 sensor in the exhaust will trigger a trouble code (and light) the minute, the very second, it gets a drop of antifreeze on it. If that happens, it means the head gasket is going out, These vehicles have some notoriety for such things.

Go to Autozone, as pointed out above, and get your codes read. If it shows O2 sensor then swap it out (it's not that hard a job or expensive a part). If you get another light soon after, and the code shows the same problem, take it to a shop which knows how to check for a head gasket problem.

The thing is in the early stages it's easier to fix than later stages, meaning it'll cost less. The O2 sensor problem pops up very early, before you start seeing oil in the coolant or coolant in the oil problems.

But you should get the code checked soon.
posted by Elvis at 9:54 AM on April 4, 2007

The O2 sensor in the exhaust will trigger a trouble code (and light) the minute, the very second, it gets a drop of antifreeze on it.

Well, that's sort of correct, but quite scaremonger-y. The oxygen sensor doesn't know that it's been antifreezed, but the engine computer(s) probably know when the O2 sensor gets sluggish or goes bad. Which can happen for a ton of reasons, including (prosaically) age. I wouldn't be surprised if the sensor was the problem in this case, but first do what paulsc suggests. .
posted by Kwantsar at 12:36 PM on April 4, 2007

If you're driving any significant distances on a regular basis and the O2 sensor is bad you should notice a pretty marked decrease in gas mileage.
posted by ganzhimself at 3:04 PM on April 4, 2007

mine has come on for a number of reasons. O2 sensor, a vacuum hose had come loose when they changed the oil (but it read as an O2 sensor probem), gas cap was loose, and even once for no good reason. My dad has his own shop and used their diagnostic device. Easy as pie.

Just stop by a auto parts/shop that will do it for free and see what they say.
posted by nimsey lou at 3:26 PM on April 4, 2007

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