OBD1 scanner question

[yacospeed]

I am using an Innova OBD1 code reader. Key on Engine on, the second I press the 'test' button, the engine immediately revs to 2500 rpms. I used this scanner a few months ago without issue and every video I have seen on youtube shows the engine staying at idle.

Anybody have this issue before? Not sure if it is a scanner issue or a car issue

 

[Mustang5L5]

Idling up the engine is part of the code reading process. Usually it idles up to 1500RPM or so.

The fact that it goes up to 2500RPM may point to an IAC issue, a vacuum leak, or a defective sensor. In other words, the ECU is trying to command 1500RPM but something is causing it to be higher.