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As I drive around town, the car functions perfectly, with the high idle as the exception.
However, when I drive on the highway, or long stretches of roadway, the Service Engine Soon light activates. How do I check this to determine what has happened to trigger the light? Even when I turn the engine off and restart, and the light stays off, the car functions normally and with no obvious symptoms. Does anyone know what I can check to affirm what needs to be repaired?
Last edited by altownsend; Dec 30, 2023 at 10:41 PM.
Have you checked to see if your car has any codes stored?
You can ground the OBD1 terminal (jump) A and B to show your codes (if any)
With your ignition key in off position , jump A and B terminals . you can use a paper clip or make one out of metal as I did
Turn the ignition key to accessories (don't start the car) , look at your service engine light.
This will start flashing, it will flash once with a small gap then flash again twice quickly. This 1-2 (code 12)combination will happen three times.
After the 1-2 has done its repeat times the light will flash any other codes the same way. example 3-2 (code 32) three times
After any other code/s have been shown , the car will let you know by flashing the 1-2 combination once again three times (test complete)
OBD1 terminal
Located by you right knee drivers side
C4 Service Engine Soon
