What makes the ECM think the IAC is bad for a P1519 code.

Question

There is no way for the ECM to monitor the IAC directly that I can tell. How does the ECM differentiate P1519 from P505?

Answer 1

Hi there

Any type of vacuum leak or reason for the engine speed to be above normal will cause the code. Usually vacuum leaks cause the issue because the idle increases as the computer adds fuel to try and make the mixture right.