AutoCodes – Generic – B123F

B123F Code - Automatic Lighting Control Unit/Sensor Internal Error

Quick Answer

The Climate Control Unit monitors the Automatic Lighting Control Unit/Sensor. Common causes include Faulty Sunlight Sensor, Sunlight Sensor harness is open or shorted, Sunlight Sensor 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: B123F indicates Automatic Lighting Control Unit/Sensor Internal Error.
Common causes: Common causes include Faulty Sunlight Sensor, Sunlight Sensor harness is open or shorted, Sunlight Sensor 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 4,525

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 Mar 05, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code B123F Description

The Climate Control Unit monitors the Automatic Lighting Control Unit/Sensor. The Climate Control Unit sets the OBDII code when the Automatic Lighting Control Unit/Sensor is not to factory specifications.

OBDII Code B123F - Automatic Lighting Control Unit/Sensor Internal Error - AutoCodes.com — B123F Code - Automatic Lighting Control Unit/Sensor Internal Error

What does this mean?

What are the Possible Causes of the DTC B123F?

Faulty Sunlight Sensor
Sunlight Sensor harness is open or shorted
Sunlight Sensor circuit poor electrical connection
Faulty Climate Control Unit

How to Fix the DTC B123F?

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 B123F 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.

Need more information about the B123F code?

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Need Help with the Code?

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Information for Specific Makes

B123F Acura — Automatic Lighting Control Unit/Sensor Internal Error
B123F Honda — Automatic Lighting Control Unit/Sensor Internal Error

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.