AutoCodes – Generic – U151C

U151C Code - HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus

Quick Answer

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. Common causes include Faulty Auxiliary Heating, Ventilation, and Air Conditioning (HVAC) Control Module, Auxiliary HVAC Control Module harness is open or shorted, Auxiliary HVAC 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: U151C indicates HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus.
Common causes: Common causes include Faulty Auxiliary Heating, Ventilation, and Air Conditioning (HVAC) Control Module, Auxiliary HVAC Control Module harness is open or shorted, Auxiliary HVAC 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 1,403

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 Jun 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U151C Description

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. The serial data is transmitted over a LIN circuit between a master control module and other LIN devices within a particular subsystem. If serial data communication is lost between any of the LIN devices on the LIN bus network, the master control module will set a no communication code against the non-communicating LIN device. The Diagnostic Trouble Code (DTC) will set when a supervised periodic message to the Heating, Ventilation, and Air Conditioning (HVAC) Control Module from the Auxiliary HVAC Control Module has not been received.

OBDII Code U151C - HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus - AutoCodes.com — U151C Code - HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus

What does this mean?

What are the Possible Causes of the DTC U151C?

Faulty Auxiliary Heating, Ventilation, and Air Conditioning (HVAC) Control Module
Auxiliary HVAC Control Module harness is open or shorted
Auxiliary HVAC Control Module circuit poor electrical connection
Faulty HVAC Control Module

How to Fix the DTC U151C?

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 U151C 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 U151C code?

Need more information on how to fix the U151C code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U151C code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U151C Buick — HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus
U151C Cadillac — HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus
U151C Chevrolet — HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus
U151C GMC — HVAC Control Module Lost Communication With Auxiliary HVAC Control Module On LIN Bus

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.

Frequently Asked Questions about U151C Code

1. What does the OBDII code U151C mean?

The U151C code indicates that the HVAC control module has lost communication with the auxiliary HVAC control module over the LIN (Local Interconnect Network) bus.

2. What are common symptoms of the U151C code?

Symptoms may include improper operation of the rear or auxiliary HVAC system, inability to adjust rear climate settings, or an illuminated check engine light or HVAC warning light.

3. What causes the U151C code to appear?

Common causes include a faulty auxiliary HVAC control module, damaged or corroded LIN bus wiring, loose electrical connections, or a malfunctioning HVAC control module.

4. How can I diagnose the U151C code?

Diagnose the code by checking for communication between the HVAC control module and the auxiliary module using a scan tool, inspecting LIN bus wiring for damage, and verifying power and ground connections.

5. Can a blown fuse cause the U151C code?

Yes, a blown fuse supplying power to the auxiliary HVAC control module can interrupt communication and trigger the U151C code.

6. Is the U151C code serious?

While not critical to vehicle operation, the U151C code can affect passenger comfort by disabling the auxiliary HVAC system, which may require prompt attention in extreme weather.

7. How do you fix the U151C code?

Repairs may involve replacing the auxiliary HVAC control module, repairing LIN bus wiring, fixing poor electrical connections, or reprogramming the HVAC control module.

8. Can a software update fix the U151C code?

In some cases, a software update for the HVAC control module can resolve communication issues if the problem is related to a programming error.

9. What tools are needed to troubleshoot the U151C code?

A diagnostic scan tool capable of reading LIN bus communication, a multimeter for testing electrical circuits, and wiring diagrams for the HVAC system are essential.

10. Can driving with the U151C code cause further damage?

Driving with this code is unlikely to cause further damage, but it may result in reduced functionality of the auxiliary HVAC system, affecting passenger comfort.