AutoCodes – Generic – U18A5

U18A5 Code - Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN Bus

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Fuel Injector Control Module, 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: U18A5 indicates Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN Bus.
Common causes: Common causes include Faulty Fuel Injector Control Module, 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 1,093

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 08, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U18A5 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 U18A5 - Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN Bus - AutoCodes.com — U18A5 Code - Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18A5?

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

How to Fix the DTC U18A5?

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 U18A5 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 U18A5 code?

Need more information on how to fix the U18A5 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U18A5 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U18A5 Buick — Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN Bus
U18A5 Cadillac — Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN Bus
U18A5 Chevrolet — Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN Bus
U18A5 GMC — Lost Communication With Fuel Injector Control Module On Powertrain Expansion CAN 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 U18A5 Code

What does the OBDII code U18A5 mean?

The OBDII code U18A5 indicates a lost communication with the fuel injector control module on the powertrain expansion CAN bus, meaning the engine control module (ECM) cannot communicate with the fuel injector control module.

What are the common symptoms of the U18A5 code?

Common symptoms may include poor engine performance, reduced fuel efficiency, engine stalling, difficulty starting, or the illumination of the check engine light.

What could cause the U18A5 code to trigger?

Possible causes include damaged wiring or connectors in the CAN bus system, a faulty fuel injector control module, a malfunctioning ECM, or software issues in the vehicle's control modules.

How can I diagnose the U18A5 code?

To diagnose the U18A5 code, start by inspecting the wiring and connectors for damage, then use a scan tool to check for additional codes and monitor live data from the fuel injector control module.

What repairs might be necessary for the U18A5 code?

Repairs may involve repairing or replacing damaged wiring or connectors, replacing the fuel injector control module, updating the ECM software, or addressing any other underlying issues identified during diagnosis.

Can I drive my vehicle with the U18A5 code?

It is not recommended to drive your vehicle with the U18A5 code, as it may lead to performance issues and could potentially cause further damage to the engine or fuel injection system.

How do I clear the U18A5 code after repairs?

You can clear the U18A5 code using an OBDII scanner by selecting the option to erase trouble codes from the system. However, ensure that any underlying issues are fully resolved before clearing the code.

Is the U18A5 code serious?

Yes, the U18A5 code can be serious as it indicates a communication failure that may affect engine performance and fuel efficiency, potentially leading to more significant issues if not addressed.

Are there any specific tools needed to fix the U18A5 code?

Basic tools include an OBDII scanner for diagnostics, a multimeter for checking electrical connections, and standard automotive tools for any necessary repairs or replacements.