what is P1506 because the engine light is on. on 2001 Ford Escape

The engine light stays on and when placed on the diagnostic scanner, the code P1506 comes up.

1 answer
This code indicates that the engine speed is greater than the engine's computer is calling for. The causes could be a defective Idle Air Control (IAC) Valve, a vacuum leak, or a wiring issue related to the IAC valve.