P1507 Code - F150online Forums


P1507 Code


Old 12-16-2003, 09:08 AM
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Unhappy P1507 Code

My 2000 Lariat had decided not to idle when cold. Autozone guys pulled a P1507 code from it, and this code relates to "idle speed control aux inputs". I don't have a clue as to where this unit is located, and Autozone can't get part. Wherezit at & what is the fix. I just retired a F150 Lariat 4X4 with 355,000 miles on it and knew where everything was, but with this 5.4L, don't got a clue
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Old 12-16-2003, 12:57 PM
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Location: Fort Worth
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It's a factory code for Idle Air Control Underspeed Error
A vacuum leak, a damaged IAC assembly, a stuck IAC valve or throttle valve typically sets code 1506 or 1507.

Since you don't have any lean codes along with this code the chances of it being a vacuum leak is minimal. The IAC can be checked with a scan tool, sensor tester or multimeter, but the problem may just be carbon buildup and it can be cleaned out with some throttle body spray cleaner once removed. If that doesn't take care of it, replace it.

O'Reileys and others have an aftermarket made by GP Sorensen. It's located behind the throttle body. Look for a yellowish cylinder directly behind the throttle body. You will most likely need to remove the black plastic throttle body cover that says 5.4 to view it. Be careful not to drop the gasket or screws down on top of the manifold or you will have a tough tome retrieving them.
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Old 12-19-2003, 09:07 AM
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Talking P1507 code

Thanks, What I really needed was the location for the IAC. However, this truck is apparantly a self-healer. I started it up yesterday morning with an outside temp. of about 35 degrees, and the sucker did like it was designed to do. The check engine lite was still on, but yesterday afternoon when I left work and started it up, the light was gone, and the idle was fine. Must have had some carbon build up that passed thru. But next time I will at least know where it is located.
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Old 12-19-2003, 09:14 AM
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Location: Maryland
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the carbon build up didn't pass through. carbon builds up as a film not big chunks that can pass like a kidney stone.

the 5.4's are famous for bad/intermittant IAC's and carbon around the throttle plate which can only be cleaned with throttle body cleaner. DO NOT USE CARB CLEANER!!!

Since your problem seems random my guess would be a stuck/slow/dirty/sticking/faulty IAC.
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Old 12-19-2003, 04:59 PM
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Next time it happens disconnect the IAC and see if the RPMs change. If they don't it is most likely that the IAC valve is stuck.
Clean or replace.


Jean Marc Chartier
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