Question about 1998 Mercury Tracer

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Idle air control valve over speed error/Code P1506

Car runs poor feels like a misfire Would it be a fairly simple task to replace the defective part? Would it effect the results of my emmisions test?Novice mechanic looking to save my sister from another rip-off dealer fixing things that arent broken please help

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  • its420_us May 11, 2010

    I work on these cars all the time, and the "misfire" you state, is a concern. Before you do anything else to the car, get a "compression test" done on it. I've seen the issue personally over 50 times, and I bet it has nothing to do with any sensor.



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It is a fairly easy to replace the valve and its hard to say if the valve will fix your problem without a diagnosis i hope this helps


  1. Disconnect the battery ground cable.

  1. Disconnect the idle air control valve electrical connector.

  1. Remove the two bolts and remove the Idle Air Control valve (IAC valve) and gasket.


  1. Follow the removal procedure in reverse order. CAUTION:
    • If scraping is necessary, make sure not to damage the idle air control valve or the throttle body gasket surfaces or drop the gasket material into the throttle body.
    • The idle air control valve has a sludge resistant design andmust not be cleaned, or damage to the anti-sludge coating may result.

Posted on May 27, 2009


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Keeps throwing up trouble codes p1506,p1151,p0302,p0171

Definition of Diagnostic Trouble Code P1506 Audi: Closed Throttle Position Switch Does Not Open/Short to Ground BMW: Idle-Speed Control Valve Opening Solenoid Control Circuit Signal High Ford: Idle Air Control Overspeed Error (see P0507) Jaguar: Idle Air Control System RPM Lower Than Expected - B Bank Kia: IAC Valve Opening Coil Voltage High Lincoln: Idle Air Control Overspeed Error (see P0507) Mazda: Idle Air Control Overspeed Error Mercury: Idle Air Control Overspeed Error (see P0507) Porsche: Throttle Jacking Unit Lower Mechanical Stop, Signal Implausible Volkswagen: Closed Throttle Position Switch Does Not Open/Short to Ground Volvo: IAC Valve Opening Signal
Definition of Diagnostic Trouble Code P1151 Audi: Bank1, Long Term Fuel Trim, Range 1 Leanness Lower Limit Exceeded BMW: Oxygen Sensor Heater Circuit Signal Intermittent (Bank 2 Sensor 1) Ford: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Jaguar: Lack of H02S-21 switch, sensor indicates lean Land Rover: Lambda control limit bank 2.Implausible signal/condition Lincoln: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Mazda: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Mercury: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Subaru: HO2S-12 Heater Circuit High Input Toyota: Coolant Path Clog Up for Coolant Heat Storage System Volkswagen: Bank1, Long Term Fuel Trim, Range 1 Leanness Lower Limit Exceeded
Definition of Diagnostic Trouble Code P0302 Category: Powertrain Definition: Cylinder 2 Misfire DetectedNote: This definition of P0302 is applied to all manufacturers
Definition of Diagnostic Trouble Code P0171 Category: Powertrain Definition: System Too Lean Bank 1Note: This definition of P0171 is applied to all manufacturers

Jun 17, 2015 | Cars & Trucks

1 Answer

What does a P1506 error code on 03 Ford Taurus SEL mean

P1506 Idle Air Control Over Speed Error.
Vacuum leak or throttle sticking:
Are the vacuum controlled heater functions working properly?
Try plugging off the Evap Emissions hoses, large and small.
Use a tire gauge to measure idle fuel pressure, both with modulator valve normal and vacuum hose off. Should be 30 and 40 psi.Measure vacuum with a gauge. I would expect near 20 inches at normal idle.I'd replace the PCV valve, and carefully inspect the hose and connections.

Aug 01, 2014 | 2003 Ford Taurus

1 Answer

Iscv 33

There is a digital stepper motor installed in the idle air control valve and it is operated by the ecm after taking all the outputs from various sensors.
Check engine light error code 33. The idle air control valve circuit open or shorted to ground. There could be three possibilities which can trigger this code and the check engine light comes on.
1. Check the wiring harness for open circuit or short to ground. Check the idle speed control valve connector for looseness,corrosion of poor contacts. Jiggle the harness at various places to find any damaged wire.
2. Idle speed control valve defective. (replace. Merely replacing the electronic part of the valve can also solve the problem)
3. ECM defective. (replace)

Dec 12, 2013 | 1999 Toyota Corolla

1 Answer

Why does my ford taurus idle high code P1506

The code is for the idle air control valve which controls idle speed.
The problem could be a faulty control valve, or a vac leak which is letting in air to the intake and bypassing the control valve.

Jan 19, 2013 | 2000 Ford Taurus

1 Answer

Misfires on cylinder number one with code,also code p1506.once it warms up vehicle runs fine

P1506-- Idle Air Control

Damaged -- IAC Valve
IAC --Stuck Open
Vacuum Leaks
Failed EVAP System

May also have a bad ignition coil on cyl#1

Apr 06, 2011 | Ford Taurus Cars & Trucks

2 Answers

Code P1506, 2002 ford taurus wagpn

P1506 Idle Air Control
Overspeed Error

IAC Valve--Bad
Vacuum Leaks
IAC Stuck Open
Failed EAVP System

Disconnect the valve--if little
or no change in RPM,then
Valve is stuck or bad

Mar 16, 2011 | 2000 Ford Taurus

1 Answer

When the car is in drive it idles up to 30 mph i got trouble p 1506

P1506 - Air Idle Control Over Speed Error

Replace the air idle control valve. Also check for vacuum leaks at the pcv valve / hose an any vacuum lines, to look for un-metered air coming in.

Jan 20, 2011 | 2002 Ford Explorer

4 Answers

How to fix problem with cod P1506 Ford explower 1998

Hello! The Idle Air Control (IAC) is setting P1506...Idle is to high...Other problems can cause the idle to over speed...It isn't the IAC in many instances...A vacuum leak is #1...The vehicle has some years on it...Go over the vacuum lines and look for weak collapsed lines, broken, or poorly seated...A defective PCV valve is #2...If it hasn't been changed in awhile it's due...Base idle should be 780 in neutral...If # 1 and #2 prove to be OK I'll take it from there...


Aug 19, 2010 | 1998 Ford Explorer

2 Answers

Check Engine light code 1506

Dear Sir,

P1506 error refers to Idle Air Control System Overspeed Detected.
So solution is check your Air control system wires,and check air control speed once again.
If this not solves your problem back with the result,leave a feedback we happy to help you.

Have a nice day

Good luck

Sep 16, 2009 | 1995 Mazda 626

1 Answer

1999 f150 4x4 , p1506

P1506 Idle Air Control Overspeed Error

The Idle Air Control (IAC) valve adjusts the engine idle speed. The valve is located on the side of the throttle body. The valve is controlled by a duty cycle signal from the PCM and allows air to bypass the throttle plate in order to maintain the proper idle speed.


  1. Turn the ignition switch to the OFF position.
  2. Disconnect the wiring harness from the IAC valve.
  3. Measure the resistance between the terminals of the valve.

Due to the diode in the solenoid, place the ohmmeter positive lead on the emphasis type="medium" VPWR/emphasis terminal and the negative lead on the emphasis type="medium" ISC/emphasis terminal.
  1. Resistance should be 6-13 ohms.
  2. If resistance is not within specification, the valve may be faulty.
Please rate and god bless:)

Apr 25, 2009 | 1999 Ford F150 Regular Cab

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