An explanation of the OBD2 design computer system on your car or truck

Why does the yellow or orange Service Engine Soon Light (SES) or Check Engine LightCome ON?

There are literally hundreds of failures or faults that can cause the car/truck computer system to turn the dashboard SES (Service Engine Soon) light ON. Some are major problems, some are minor.

Your vehicle has an emission computer system controlling it called an OBD2 system.
Most cars and trucks built since 1994 have this system.
The computer system on your vehicle does continuous monitoring of its circuits.
These self-tests are called monitors.

The computer constantly performs these tests to make sure everything is operating properly and that the vehicle emissions meet federal standards.
Some of the tests the computer does take only a short time to complete.
Other tests may require weeks of driving in a variety of conditions.

We have done the computer system repairs that needed to be performed on your vehicle today. We have cleared the trouble codes from the computer memory, and we have given it several test-drives.

The Service Engine Soon light has not come back on for us in our driving, and all systems are operating properly. But we will not know for sure whether any other problems are in the system until all these drive cycles are made.

As we mentioned above, it could take weeks for some of these tests to be completed.
We wanted you to be aware of that and ask that you let us know if the Service Engine Soon light comes on at any time in the future.

Back to Questions & Answers