AutoCodes – GMC – U1800 GMC

U1800 GMC Code - Lost Communications With Fuel Injector Control Module

Quick Answer

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Fuel Injector Control Module (FICM), Fuel Injector Control Module harness is open or shorted, Fuel Injector 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: U1800 GMC indicates Lost Communications With Fuel Injector Control Module.
Common causes: Common causes include Faulty Fuel Injector Control Module (FICM), Fuel Injector Control Module harness is open or shorted, Fuel Injector 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 4,283

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 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1800 GMC Description

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication Diagnostic Trouble Code (DTC) set by other modules that depend on information from that failed module. If any of the CAN circuit are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a Diagnostic Trouble Code will set.

OBDII Code U1800 GMC - Lost Communications With Fuel Injector Control Module - AutoCodes.com — U1800 GMC Code - Lost Communications With Fuel Injector Control Module

What does this mean?

What are the Possible Causes of the DTC U1800 GMC?

Faulty Fuel Injector Control Module (FICM)
Fuel Injector Control Module harness is open or shorted
Fuel Injector Control Module circuit poor electrical connection

How to Fix the DTC U1800 GMC?

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 U1800 GMC 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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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 U1800 GMC Code

1. What are the common symptoms of OBDII code U1800 GMC (Lost Communications With Fuel Injector Control Module)?

- Common symptoms include engine misfires, rough idling, poor fuel efficiency, and the illumination of the check engine light.

2. What are the possible causes of the U1800 GMC code?

- The U1800 code can be caused by issues such as a faulty fuel injector control module, damaged wiring or connectors, or a communication network error.

3. How can I diagnose the U1800 GMC code?

- Diagnosis typically involves using an OBDII scanner to retrieve the code, checking for other related codes, inspecting the wiring and connectors, and testing the fuel injector control module.

4. What repair tips can help fix the U1800 GMC code?

- Repair tips may include repairing or replacing damaged wiring, connectors, or the fuel injector control module, ensuring proper ground connections, and performing a reprogramming of the control module.

5. Can I drive my vehicle with the U1800 GMC code?

- It is not recommended to drive your vehicle with the U1800 code present, as it can lead to further damage and potential safety issues. It is best to address the issue as soon as possible.

6. How much does it cost to repair the U1800 GMC code?

- The cost of repair can vary depending on the underlying cause of the code and whether you choose to do the repairs yourself or take your vehicle to a mechanic. Costs may range from a few hundred to a few thousand dollars.

7. Is the U1800 GMC code a common issue in GMC vehicles?

- The U1800 code is not as common as some other OBDII codes, but it can still occur in GMC vehicles, especially in older models or vehicles with high mileage.

8. Can a DIY enthusiast fix the U1800 GMC code?

- Depending on your experience and access to tools, a DIY enthusiast may be able to diagnose and repair the U1800 code. However, complex electrical issues may require professional help.

9. How long does it take to repair the U1800 GMC code?

- The repair time for the U1800 code can vary based on the specific issue causing the code, the availability of parts, and the skill level of the person performing the repairs. It could take anywhere from a few hours to a full day.

10. Are there any preventative measures to avoid the U1800 GMC code in the future?

- Regular maintenance, such as checking and cleaning connectors, inspecting wiring for damage, and ensuring proper grounding, can help prevent issues that may trigger the U1800 code.