AutoCodes – Chevrolet – U1818 Chevrolet

U1818 Chevrolet Code - Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus

Quick Answer

Devices connected to the powertrain high-speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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: U1818 Chevrolet indicates Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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 2,252

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jul 24, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1818 Chevrolet Description

Devices connected to the powertrain high-speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device.
The Diagnostic Trouble Code (DTC) will be set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U1818 Chevrolet - Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus - AutoCodes.com — U1818 Chevrolet Code - Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus

What does this mean?

What are the Possible Causes of the DTC U1818 Chevrolet?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC U1818 Chevrolet?

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 U1818 Chevrolet 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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Need more information on how to fix the U1818 Chevrolet code? Get Access to Factory Service Manuals

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Get the U1818 Chevrolet code diagnosed by a professional: Find a repair shop in your area

Information for Specific Chevrolet Models

U1818 2014 Chevrolet Silverado — Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus
U1818 2015 Chevrolet Silverado — Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus
U1818 2016 Chevrolet Silverado — Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus
U1818 2017 Chevrolet Silverado — Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus
U1818 2018 Chevrolet Silverado — Lost Communication with Engine Control Module on Powertrain Expansion Communication 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 U1818 Chevrolet Code

1. What are the common symptoms of OBDII code U1818 in a Chevrolet?

The common symptoms include engine stalling, rough idling, poor acceleration, and the illumination of the check engine light.

2. What does the OBDII code U1818 "Lost Communication with Engine Control Module on Powertrain Expansion Communication Bus" mean?

This code indicates a communication error between the Engine Control Module (ECM) and other modules on the Powertrain Expansion Communication Bus.

3. What can cause the U1818 code to appear in a Chevrolet?

Possible causes include faulty wiring or connections, a malfunctioning ECM, issues with the communication bus, or a software glitch.

4. How can I diagnose the U1818 code in my Chevrolet?

Diagnosis typically involves checking the wiring and connections related to the Powertrain Expansion Communication Bus, testing the ECM for proper function, and scanning for other related trouble codes.

5. Is it safe to drive with the U1818 code present in a Chevrolet?

It is not recommended to drive the vehicle with this code present, as it can lead to potential drivability issues and further damage if left unresolved.

6. Can I repair the U1818 code in my Chevrolet myself?

While some basic checks like inspecting connections can be done by DIY enthusiasts, diagnosing and repairing the root cause of the code may require professional assistance due to the complexity of the vehicle's communication systems.

7. How much does it typically cost to fix the U1818 code in a Chevrolet?

The cost of repairs can vary depending on the underlying issue causing the code. It may range from a simple wiring repair to a more involved ECM replacement, so seeking a diagnostic from a qualified mechanic is advisable.

8. Will resetting the trouble codes make the U1818 code disappear permanently?

Resetting the codes may temporarily clear the check engine light, but if the underlying issue causing the U1818 code is not addressed, it is likely to reappear after some driving cycles.

9. Can extreme weather conditions trigger the U1818 code in a Chevrolet?

Extreme weather conditions can sometimes lead to electrical issues that may trigger communication errors, potentially causing the U1818 code to appear.

10. Are there any preventive measures to avoid the U1818 code in a Chevrolet?

Regular vehicle maintenance, including checking and cleaning electrical connections, can help prevent communication errors that may trigger the U1818 code.