AutoCodes – Mercury – P1506 Mercury

P1506 Mercury Code - Idle Air Control Overspeed Error

Quick Answer

The Idle Air Control Valve (IACV) valve assembly controls the engine idle speed and provides a dashpot function. Common causes include Faulty Idle Air Control (IAC) valve, IAC valve harness is open or shorted, IAC valve circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1506 Mercury indicates Idle Air Control Overspeed Error.
Common causes: Common causes include Faulty Idle Air Control (IAC) valve, IAC valve harness is open or shorted, IAC valve circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 4,677

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 25, 2019

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P1506 Mercury Description

The Idle Air Control Valve (IACV) valve assembly controls the engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The Powertrain Control Module (PCM) determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine RPM and increases or decreases the IAC duty cycle in order to achieve the desired RPM.

OBDII Code P1506 Mercury - Idle Air Control Overspeed Error - AutoCodes.com — P1506 Mercury Code - Idle Air Control Overspeed Error

What does this mean?

What are the Possible Causes of the DTC P1506 Mercury?

Faulty Idle Air Control (IAC) valve
IAC valve harness is open or shorted
IAC valve circuit poor electrical connection
Intake leaks
Stuck PCV Valve

How to Fix the DTC P1506 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The P1506 code means that the engine idle is out of factory specification. Sometimes the Idle Air Control (IAC) may have carbon built up. Disconnect the car battery, remove the valve, clean, re-install valve, and drive the vehicle for about 5 minutes with the headlights and A/C ON to get the idle relearned.
Also, check for intake leaks or stuck PCV Valve.
If the problem persistss, the IAC valve may need to be replaced.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1506 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.