The Check Engine Light comes on after about 20-30 minutes of driving but when I immediately try to check the code with the jumper in place, there is no code stored. Therefore I can't check the code the normal method.

Obviously, some sensor is reading out of spec but I can't tell which sensor until I can read the code. Is there any way of determining the cause of the Check Engine Light without turning off the vehicle?

The car is a 92 Civic Ex.

 

Yes

 

obd1 cars yes, obd2 cars most def can.

 

Jump the 2 pin connector near passenger side kick panel before shutting off the car and you can read the blink sequence of the cel