AutoCodes – GMC – U1803 2018 GMC Sierra

U1803 2018 GMC Sierra 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: U1803 2018 GMC Sierra 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 165

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code U1803 2018 GMC Sierra 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 U1803 2018 GMC Sierra - Lost Communication with Hybrid/EV Powertrain Control Module 2 - AutoCodes.com — U1803 2018 GMC Sierra Code - Lost Communication with Hybrid/EV Powertrain Control Module 2

What does this mean?

What are the Possible Causes of the DTC U1803 2018 GMC Sierra?

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 U1803 2018 GMC Sierra?

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 U1803 2018 GMC Sierra 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 U1803 2018 GMC Sierra code?

Need more information on how to fix the U1803 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1803 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 U1803 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code U1803 in a 2018 GMC Sierra?

- Common symptoms include the hybrid/EV powertrain malfunction indicator light coming on, issues with the vehicle's hybrid or electric powertrain operation, and potential loss of communication with the powertrain control module 2.

2. What can cause the OBDII code U1803 to trigger in a 2018 GMC Sierra?

- The code U1803 typically triggers when there is a communication breakdown between the vehicle's onboard diagnostic system and the hybrid/EV powertrain control module 2, which could be due to wiring issues, module failure, or software glitches.

3. How serious is the U1803 code in a 2018 GMC Sierra?

- The U1803 code indicating lost communication with the hybrid/EV powertrain control module 2 should be addressed promptly as it can affect the proper functioning of the vehicle's hybrid or electric powertrain system.

4. What are some DIY repair tips for resolving the U1803 code in a 2018 GMC Sierra?

- DIY repair tips may include checking for loose or damaged wiring connections related to the hybrid/EV powertrain control module 2, ensuring the module is securely connected, and performing a reset by disconnecting the vehicle's battery for a few minutes.

5. Can a mechanic easily diagnose and repair the U1803 code in a 2018 GMC Sierra?

- A qualified mechanic with the necessary diagnostic tools can efficiently diagnose the U1803 code by conducting a thorough inspection of the vehicle's hybrid/EV powertrain system, identifying the source of communication loss, and performing the required repairs or module replacement.

6. Is it safe to continue driving a 2018 GMC Sierra with the U1803 code present?

- It is not recommended to drive the vehicle with the U1803 code active, as it can potentially lead to further issues with the hybrid or electric powertrain system and affect the overall performance and safety of the vehicle.

7. How much can it cost to repair the U1803 code in a 2018 GMC Sierra?

- The cost of repairing the U1803 code can vary depending on the underlying cause, such as wiring repairs, module replacement, or software updates. It is advisable to consult with a mechanic to get an accurate estimate for the repairs.

8. Can a software update fix the U1803 code in a 2018 GMC Sierra?

- In some cases, a software update provided by the manufacturer may resolve the communication issue causing the U1803 code. It is recommended to check with a GMC dealership or authorized service center for information on available updates.

9. How can I prevent the U1803 code from reoccurring in my 2018 GMC Sierra?

- To prevent the U1803 code from reoccurring, it is essential to maintain regular vehicle inspections, address any communication-related issues promptly, and follow the manufacturer's recommended maintenance schedule for the hybrid/EV powertrain system.

10. Will resetting the OBDII system clear the U1803 code in a 2018 GMC Sierra?

- Resetting the OBDII system by disconnecting the battery may temporarily clear the U1803 code, but if the underlying issue causing the communication loss with the hybrid/EV powertrain control module 2 is not addressed, the code is likely to reappear.