AutoCodes – Generic – U179A

U179A Code - Lost Communication with Hybrid/EV Powertrain Control Module 2

Quick Answer

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Common causes include Faulty Hybrid/EV Powertrain Control Module 2, Hybrid/EV Powertrain Control Module 2 harness is open or shorted, Hybrid/EV Powertrain Control Module 2 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: U179A indicates Lost Communication with Hybrid/EV Powertrain Control Module 2.
Common causes: Common causes include Faulty Hybrid/EV Powertrain Control Module 2, Hybrid/EV Powertrain Control Module 2 harness is open or shorted, Hybrid/EV Powertrain Control Module 2 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 1,482

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 Jul 21, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U179A Description

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Once the scan tool is connected to the serial data circuit through the Data Link Connector (DLC), the scan tool can be used to monitor each device for diagnostic purposes and to check for Diagnostic Trouble Codes (DTC). When the vehicle is ON, each device communicating on the serial data circuit sends a state of health message to ensure that the device is operating properly. When a device stops communicating on the serial data circuit, for example, if the device loses power or ground, the state of health message it normally sends on the serial data circuit disappears. Other devices on the serial data circuit, which expect to receive that state of health message, detect its absence; those devices in turn set a DTC associated with the loss of state of health of the non-communicating device. A loss of serial data communications DTC does not represent a failure of the devices that contain the stored DTC.

OBDII Code U179A - Lost Communication with Hybrid/EV Powertrain Control Module 2 - AutoCodes.com — U179A Code - Lost Communication with Hybrid/EV Powertrain Control Module 2

What does this mean?

What are the Possible Causes of the DTC U179A?

Faulty Hybrid/EV Powertrain Control Module 2
Hybrid/EV Powertrain Control Module 2 harness is open or shorted
Hybrid/EV Powertrain Control Module 2 circuit poor electrical connection

How to Fix the DTC U179A?

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 U179A 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 U179A code?

Need more information on how to fix the U179A code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U179A code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U179A Buick — Lost Communication with Hybrid/EV Powertrain Control Module 2
U179A Cadillac — Lost Communication with Hybrid/EV Powertrain Control Module 2
U179A Chevrolet — Lost Communication with Hybrid/EV Powertrain Control Module 2
U179A GMC — Lost Communication with Hybrid/EV Powertrain Control Module 2

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 U179A Code

1. What does the OBDII code U179A mean?

The U179A code indicates a loss of communication with Hybrid/EV Powertrain Control Module 2, which manages specific functions in hybrid or electric vehicles.

2. What are the common symptoms of the U179A code?

Symptoms may include the illumination of the check engine light, reduced vehicle performance, issues with charging or power delivery, or the inability to start the vehicle.

3. What causes the U179A code to appear?

Common causes include damaged wiring or connectors, a malfunctioning Powertrain Control Module 2, low or failing auxiliary battery voltage, or network communication issues.

4. Can the U179A code cause serious vehicle issues?

Yes, if unresolved, it can lead to significant drivability problems, such as reduced power output or a complete inability to operate the vehicle.

5. How is the U179A code diagnosed?

A technician will use a scan tool to confirm the code, inspect the wiring and connectors for damage, test the communication network, and check the voltage levels of the vehicle's electrical systems.

6. Can a weak battery trigger the U179A code?

Yes, a weak or failing 12V auxiliary battery can disrupt communication between modules and trigger this code.

7. Is the U179A code specific to any vehicle make or model?

This code is most commonly found in hybrid and electric vehicles, but the affected models and specific module functions may vary by manufacturer.

8. What repairs are needed to fix the U179A code?

Repairs may include fixing or replacing damaged wiring or connectors, reprogramming or replacing the affected module, or addressing battery and voltage issues.

9. Can I drive with the U179A code active?

Driving may be possible but is not recommended, as the vehicle could experience reduced performance or fail to operate entirely.

10. How much does it cost to fix the U179A code?

Costs vary depending on the root cause but may include diagnostic fees, wiring repairs, or module replacement, typically ranging from $100 to $1,000 or more.