Fix It and keep it

We are the proud owners of a 2003 Toyota Matrix that we bought in the fall of 2002. For the most part it has been a good dependable car. It seats four adults comfortably and is a snap to park in tight places. The gas mileage isn’t bad either at 29 to 33 miles per gallon around town and highway.

One pesky issue with the Matrix that we have been having is the check engine light comes on from time to time and then goes out by itself. I was going to the dealership to have it looked at when the light just went off. So as not look like an idiot I never went to have it looked at by a dealer mechanic.

After speaking to several people about the Matrix and the check engine light problem I learned that the trouble code that is being set is in the fuel evaporator system. It seems that the fuel evaporator systems on the Matrix are sensitive to vacuum changes within the system that can be caused by simply not tightening the gas cap tight enough. There are more serious causes for this problem with the fuel evaporator system but the gas cap being lose or defective is the most common cause especially if the light goes on and off by itself. If there were a real problem the light would stay on until it was diagnosed and reset by a mechanic.

After learning that the evaporator control system was located above the rear suspension system I wasn’t really anxious to disturb that unless it was really the cause of the problem. I decided to do the easy work first and check for vacuum leaks and any other type of seal issues with the gas cap. What I found that seemed to correct the problem was the gas cap seal was contaminated by some type of sticky thread that must have come from a gas pump nozzle. The sticky thread was stuck so tight to the gas fill neck on the Matrix that it looked like it was supposed to be there. The thread was causing the gas cap not to seal that caused the check engine light to come on when the vacuum wasn’t what it should have been within the evaporator fuel system. The tread on the fill neck was the same reason that a new gas cap didn’t fix the problem either.

So if you are having intermittent check engine light, check your gas cap and the fill neck to be sure that you are getting a good seal so the right vacuum can be developed in the system.