Q. Lately, I have read five of your answers to the questions about the situation when the check-engine light comes on. At the end of March, our ’93 Ford Escort had the same problem after the exhaust system was replaced. I talked to a Ford dealer about the check-engine light coming on and was told an engine diagnostic was needed. What information should I get from an engine diagnostic?
W.H., Elk Grove Village
A. The check-engine light (more appropriately called the malfunction indicator lamp) glows whenever there is a, well, malfunction.
If the light comes on, then goes off, there was a brief malfunction that went away. But to help the technician, the car’s onboard computer makes a note of the malfunction and retains that in its memory–generally until you restart the car 50 times. This gives you enough time to make an appointment for service.
The technician uses a special device that interrogates the computer, which gives him a clue as to where the malfunction may be. It does not tell him what precisely went wrong, only in what subsystem the malfunction occurred. The technician then does an in-depth diagnosis of the subsystem.
If the malfunction indicator light comes on and stays on, there is a hard fault that has not gone away. Driving your car while the light is on may cause excessive tailpipe emissions and, perhaps, drivability problems. Take your car in for service as soon as possible.
Q. The enclosed invoice tells the story of our problem. We took our 1992 Mercury Marquis in for an oil change, and the person told my husband that there were large flakes of rust on the oil pan and it was leaking through in various places. Does replacing an oil pan happen often?
M.E.N., Chicago
A. There are probably millions of cars in junkyards whose oil pans are in perfect shape. They are probably all pre-1990 vintage. Modern oil pans have become so thin that soon you may be able to see the oil in them. We think it is part of the carmakers’ weight reduction programs and rusting pans are, well, pandemic. It just seems that Ford has a bigger problem than others.
Fortunately the pan is relatively inexpensive. Unfortunately, the labor to replace it is very expensive. Your invoice tells that story quite clearly.
Q. We just bought our new car in March and the doors leak air terribly, especially on windy days. Have you had other complaints about this model or is it just our car? We have had other Hondas and never had this problem before.
Mrs. C.R., Peru
A. From your letter, we are not sure which model Honda you bought, but wind leaks do happen to all makes. Sometimes it is a problem with the door seals; other times it is a misalignment of the doors. Seals can be replaced and doors realigned. Your dealer will take care of it for you under warranty.
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Bob Weber is an ASE-certified Master Automobile Technician, having recertified every five years since 1978. Address your technical questions about cars and trucksto him in care of Motormouth, 17717 Silcott Springs Rd., Purcellville, Va., 20132. Send e-mail, including name and town, to MMTribune@netscape.net. Answers will be supplied only through the paper.
