AutoCodes – Generic – U0181

U0181 Code - Lost Communication With Headlamp Leveling Control Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty Headlamp Leveling Control Module, Headlamp Leveling Control Module harness is open or shorted, Headlamp Leveling Control Module 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: U0181 indicates Lost Communication With Headlamp Leveling Control Module.
Common causes: Common causes include Faulty Headlamp Leveling Control Module, Headlamp Leveling Control Module harness is open or shorted, Headlamp Leveling Control Module 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 10,051

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 Apr 02, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code U0181 Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Headlamp Leveling Control Module has not been received.

OBDII Code U0181 - Lost Communication With Headlamp Leveling Control Module - AutoCodes.com — U0181 Code - Lost Communication With Headlamp Leveling Control Module

What does this mean?

What are the Possible Causes of the DTC U0181?

Faulty Headlamp Leveling Control Module
Headlamp Leveling Control Module harness is open or shorted
Headlamp Leveling Control Module circuit poor electrical connection

How to Fix the DTC U0181?

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 U0181 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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Information for Specific Makes

U0181 Buick — Lost Communication With Headlamp Leveling Control Module
U0181 Cadillac — Lost Communication With Headlamp Leveling Control Module
U0181 Chevrolet — Lost Communication With Headlamp Leveling Control Module
U0181 GMC — Lost Communication With Headlamp Leveling Control Module
U0181 Pontiac — Lost Communication With Headlamp Leveling Control Module
U0181 Saturn — Lost Communication With Headlamp Leveling Control Module

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.