hey guys, first post on the forum but am active on other car forums. just bought a 99 cherokee sport 4.0l l6 and the check engine light came on for code p1509 which is "idle air control circuit open". I've searched this forum and can't find a single post even mentioning this code. anyone ever have this before? the idle is a little shaky but doesn't surge.

so far I've done an oil change, cap, rotor, wires, plugs, and a new battery. in the middle of replacing the nss, was gonna just clean it but I broke it taking it off.

I'm gonna clean the throttle body and iac next weekend and look for vacuum leaks, just want to see if anyone else has had this code and am open to other suggestions, thanks

I think the DTC code has changed. Can't find P1509 anywhere.


That aside, you might want to unplug the IAC and examine the pin cavities in the connector for corrosion.


Then, using an Ohmmeter, do the resistance checks (below) at the IAC to see if the IAC stepper motor is defective.

thanks for the info, what do you mean by the code changing? not too familiar with obd2 as the majority of the cars I work on are all obd1. will definitely get some readings tomorrow, thanks again

Verify your code reader/scanner is set up for a Chrysler product. The P1XXX codes are manufacture specific.