AutoCodes – Mercury – P1397 Mercury

P1397 Mercury Code - System Voltage Out Of Self Test Range

Quick Answer

The P1397 code indicates that the 12-volt system voltage is too high or too low during the Key On Engine Off (KOEO) or key on engine running (KOER) self-test. Common causes include Alternator belt loose or missing, Low battery voltage, Faulty Charging System. 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: P1397 Mercury indicates System Voltage Out Of Self Test Range.
Common causes: Common causes include Alternator belt loose or missing, Low battery voltage, Faulty Charging System.
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 1,902

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 Aug 18, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P1397 Mercury Description

The P1397 code indicates that the 12-volt system voltage is too high or too low during the Key On Engine Off (KOEO) or key on engine running (KOER) self-test. It sets if the system voltage falls below or exceeds the calibrated threshold at any time during the KOEO or KOER self-test.

OBDII Code P1397 Mercury - System Voltage Out Of Self Test Range - AutoCodes.com — P1397 Mercury Code - System Voltage Out Of Self Test Range

What does this mean?

What are the Possible Causes of the DTC P1397 Mercury?

Alternator belt loose or missing
Low battery voltage
Faulty Charging System

How to Fix the DTC P1397 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 P1397 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.