AutoCodes – Generic – B1128

B1128 Code - Driver Side Door Lock Switch Signal Error

Quick Answer

The Door Multiplex Control Unit monitors the Driver Side Door Lock Switch. Common causes include Faulty Driver Side Door Lock Switch, Driver Side Door Lock Switch harness is open or shorted, Driver Side Door Lock Switch circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B1128 indicates Driver Side Door Lock Switch Signal Error.
Common causes: Common causes include Faulty Driver Side Door Lock Switch, Driver Side Door Lock Switch harness is open or shorted, Driver Side Door Lock Switch circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 3,852

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 19, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code B1128 Description

The Door Multiplex Control Unit monitors the Driver Side Door Lock Switch. The Door Multiplex Control Unit sets the OBDII code when the Driver Side Door Lock Switch is not to factory specifications.

OBDII Code B1128 - Driver Side Door Lock Switch Signal Error - AutoCodes.com — B1128 Code - Driver Side Door Lock Switch Signal Error

What does this mean?

What are the Possible Causes of the DTC B1128?

Faulty Driver Side Door Lock Switch
Driver Side Door Lock Switch harness is open or shorted
Driver Side Door Lock Switch circuit poor electrical connection
Faulty Door Multiplex Control Unit

How to Fix the DTC B1128?

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 B1128 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 B1128 code?

Need more information on how to fix the B1128 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B1128 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B1128 Acura — Driver Side Door Lock Switch Signal Error
B1128 Honda — Driver Side Door Lock Switch Signal 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.