AutoCodes – Mercury – P0506 Mercury

P0506 Mercury Code - Idle Speed Control System RPM Lower Than Expected

Quick Answer

The Powertrain Control Module (PCM) controls the engine idle speed to a specified level through the fine adjustment of the air, which is let into the intake manifold, by operating the Electronic Throttle Actuator Control (TAC). Common causes include Intake air restriction, Vacuum leaks, Dirty Throttle Body. 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: P0506 Mercury indicates Idle Speed Control System RPM Lower Than Expected.
Common causes: Common causes include Intake air restriction, Vacuum leaks, Dirty Throttle Body.
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 17,913

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 Jun 29, 2022

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
Comments
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Code P0506 Mercury Description

The Powertrain Control Module (PCM) controls the engine idle speed to a specified level through the fine adjustment of the air, which is let into the intake manifold, by operating the Electronic Throttle Actuator Control (TAC). The operating of the throttle valve is varied to allow for optimum control of the engine idling speed. The PCM calculates the actual engine speed from the signals of the crankshaft position sensor (POS) and the camshaft position sensor.
The PCM controls the Electronic Throttle Actuator Control so that the engine speed coincides with the target value memorized in the PCM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the PCM is determined by taking into consideration various engine conditions, such as during warming up, deceleration, and engine load (air conditioner, power steering, and cooling fan operation, etc.).
The Diagnostic Trouble Code (DTC) will set the idle speed is less than the target idle speed by 100 rpm or more.

OBDII Code P0506 Mercury - Idle Speed Control System RPM Lower Than Expected - AutoCodes.com — P0506 Mercury Code - Idle Speed Control System RPM Lower Than Expected

What does this mean?

What are the Possible Causes of the DTC P0506 Mercury?

Intake air restriction
Vacuum leaks
Dirty Throttle Body
Faulty Electronic Throttle Actuator Control (TAC)
Electronic Throttle Actuator Control harness is open or shorted
Electronic Throttle Actuator Control circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P0506 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

There is a factory service bulletin for the following Mercury Models:
2005-2007 Mercury Grand Marquis
2006-2007 Mercury Mountaineer
Mercury Factory Service Bulletin OBDII Code P0506

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0506 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.