AutoCodes – GMC – U18A2 2016 GMC Sierra

U18A2 2016 GMC Sierra Code - Lost Communication with Fuel Pump Driver Control Module

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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: U18A2 2016 GMC Sierra indicates Lost Communication with Fuel Pump Driver Control Module.
Common causes: Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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 356

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 Apr 14, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U18A2 2016 GMC Sierra Description

Devices connected to the 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 set a supervised periodic message that includes the transmitter device availability that has not been received.

OBDII Code U18A2 2016 GMC Sierra - Lost Communication with Fuel Pump Driver Control Module - AutoCodes.com — U18A2 2016 GMC Sierra Code - Lost Communication with Fuel Pump Driver Control Module

What does this mean?

What are the Possible Causes of the DTC U18A2 2016 GMC Sierra?

Faulty Fuel Pump Driver Control Module
Fuel Pump Driver Control Module harness is open or shorted
Fuel Pump Driver Control Module circuit poor electrical connection

How to Fix the DTC U18A2 2016 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 does this mean?

Code Tech Notes

There is a Factory Service Bulletin for the following Chevrolet Models:

- 2014-2018 Chevrolet Silverado
- 2015-2018 Chevrolet Suburban
- 2015-2018 Chevrolet Tahoe

If the Diagnostic Trouble Codes (DTC) P2635, U0074, and/or U18A2 are set, it may be found that the actual fuel pressure (low-pressure system) will be reading substantially higher than desired fuel pressure, in this case, the cause of the problem is a loss of communication between Engine Control Module (ECM) and Fuel Pump Control Module (FPCM).

- Diagnose for any communication DTCs set (U0074 would take priority over U18A2 if both set) before addressing DTC P2635.
- If DTC P2635 is not resolved by correcting the communication DTCs, only then should diagnose the DTC P2635.
- It has been found that a communication issue between the FPCM and ECM can potentially induce DTC P2635 and result in a pressure differential between actual and desired fuel system pressures.
- If the actual fuel pressure is substantially higher than desired (10 psi / 70 kPa or more), replacement of the fuel pump control module or fuel system components typically will not resolve this issue.
- If the actual fuel pressure is substantially lower than desired (10 psi / 70 kPa or more), this Factory Service Bulletin would NOT apply. It would be recommended to diagnose low actual fuel pressure.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U18A2 2016 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 U18A2 2016 GMC Sierra code?

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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 U18A2 2016 GMC Sierra Code

1. What does the OBDII code U18A2 for a 2016 GMC Sierra mean?

- The code U18A2 indicates a "Lost Communication with Fuel Pump Driver Control Module" error in the vehicle's onboard diagnostics system.

2. What are the common symptoms of a U18A2 code in a 2016 GMC Sierra?

- Common symptoms may include the vehicle stalling, rough idling, difficulty starting, or the fuel pump not functioning properly.

3. What are the possible causes of a U18A2 code in a 2016 GMC Sierra?

- The code U18A2 can be triggered by issues such as a faulty fuel pump driver control module, damaged wiring or connectors, a blown fuse, or a communication network problem.

4. How can I diagnose a U18A2 code in my 2016 GMC Sierra?

- Diagnosing a U18A2 code typically involves checking the fuel pump driver control module, inspecting the wiring and connectors for any damage, and verifying that the communication network is functioning correctly.

5. Can a U18A2 code in a 2016 GMC Sierra be fixed by resetting the system?

- Resetting the system may temporarily clear the code, but it is essential to address the underlying issue causing the communication error with the fuel pump driver control module.

6. What are some repair tips for resolving a U18A2 code in a 2016 GMC Sierra?

- Repair tips may include checking and repairing any damaged wiring, replacing the fuel pump driver control module if necessary, ensuring all connections are secure, and conducting a thorough inspection of the fuel pump system.

7. Is it safe to continue driving with a U18A2 code in a 2016 GMC Sierra?

- It is not recommended to drive the vehicle with a U18A2 code present, as it can lead to potential fuel pump failure and other related issues that may affect the vehicle's performance and safety.

8. Can a DIY enthusiast fix a U18A2 code in a 2016 GMC Sierra, or is professional help necessary?

- The complexity of the repair may vary depending on the underlying cause of the U18A2 code. While some DIY enthusiasts may be able to address certain issues like checking and repairing wiring, professional help may be needed for more complex repairs involving the fuel pump driver control module.

9. How much does it typically cost to repair a U18A2 code in a 2016 GMC Sierra at a dealership or auto shop?

- The cost of repairing a U18A2 code can vary depending on the specific issue, parts needed, labor costs, and whether the repair is done at a dealership or an independent auto shop. It is advisable to obtain quotes from different service providers.

10. Are there any preventive measures to avoid encountering a U18A2 code in a 2016 GMC Sierra in the future?

- Regular maintenance, such as checking the fuel pump system, inspecting wiring for damage, and ensuring proper electrical connections, can help prevent issues leading to a U18A2 code in the future.