AutoCodes – Mercury – P0A09 Mercury

P0A09 Mercury Code - DC/DC Converter Status Circuit Low

Quick Answer

The Powertrain Control Module (PCM) controls the DC/DC enable hardwired signal to switch the DC/DC converter on and off. Common causes include Faulty DC/DC Converter, DC/DC Converter harness is open or shorted, DC/DC Converter 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: P0A09 Mercury indicates DC/DC Converter Status Circuit Low.
Common causes: Common causes include Faulty DC/DC Converter, DC/DC Converter harness is open or shorted, DC/DC Converter 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 1,698

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 11, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0A09 Mercury Description

The Powertrain Control Module (PCM) controls the DC/DC enable hardwired signal to switch the DC/DC converter on and off. The DC/DC converter provides feedback to the PCM using the hardwired DC/DC fault signal. The DC/DC fault signal indicates to the PCM when the converter is non-operational or when a fault has occurred.

OBDII Code P0A09 Mercury - DC/DC Converter Status Circuit Low - AutoCodes.com — P0A09 Mercury Code - DC/DC Converter Status Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0A09 Mercury?

Faulty DC/DC Converter
DC/DC Converter harness is open or shorted
DC/DC Converter circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P0A09 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0A09 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.