I have had a P1507 CEL for the past 3+ months. I my mechanic and myself have tried evertyhing to fix the problem, including replacing the Idle Control valve, which is what the CEL is for. Still idling very low (300rpm) irratically. I have no clue what to do next. The car only has 70k miles on it. The P1507 continually keeps coming back. The idle is low.

 

My question is...The local dealer offers a computer analysis & diagnosis for $70. Will they give me more info that the generic code reader? Is it worth $70? Any advice on what the dealer can do would be of great help since I'm out of ideas. Thanks

P1507 says the ECU applied current to the IAC (Idle Air Control valve) and the RPM did NOT change.

 

Either you have a vacuum leak, hose off, loose intake manifold, loose throttle body etc. Maybe spray some brake kleen, wd-40 etc around intake and listen for change in idle to help locate the leak.

 

OR since you replaced the IAC, maybe one of the air passages coming to it or going after the throttle plate are clogged since your idle is so low. Or maybe the IAC valve is sticking and not moving.

 

Could also be that the IAC has a bad connection or broken wire either from the Main Relay (supplies +12V) or from the IAC to the ECU.

 

I don't know what any further code pulls would reveal unless there is another code accompanying the P1507.

 

Good Luck finding problem.

Also as I just replied in another thread, it could be the Neutral switch on the transmission. In your case, the car may think it's in neutral when it's really in gear thereby keeping the idle low.

 

Just another thought.