Damaged or corroded wiring on the Bus D circuit, including chafed insulation, broken wires, or poor connector pins; A failed module that is supposed to communicate on Bus D, causing the bus to go silent or drag down the network; Water intrusion or contamination in a connector or module housing on the Bus D segment; Loose or corroded battery terminals or ground connections that disrupt module power and communication; Aftermarket accessories improperly tapped into the bus wiring, introducing noise or a short; A faulty gateway module or central communication interface that routes messages between buses; Software or configuration mismatch in a module that prevents it from joining Bus D correctly

DTC codes / U00xx · Network wiring and bus faults / U0055

U0055Vehicle Communication Bus D

Q: What does code U0055 mean?

Vehicle Communication Bus D. U0055 indicates that the vehicle's communication network has lost contact with a module assigned to Communication Bus D, which is one of several data buses used for module-to-module messaging. The computer that stores this code has detected that expected messages from that bus are missing or corrupted, often due to an open circuit, a short, or a failed module on that bus segment.

U0055 indicates that the vehicle's communication network has lost contact with a module assigned to Communication Bus D, which is one of several data buses used for module-to-module messaging. The computer that stores this code has detected that expected messages from that bus are missing or corrupted, often due to an open circuit, a short, or a failed module on that bus segment.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaNetwork wiring and bus faults

Symptoms you may notice

Illumination of the malfunction indicator lamp (MIL) or a dedicated communication fault light
Multiple warning lights on the dashboard, such as ABS, airbag, or traction control, because several modules share the bus
Intermittent or complete failure of features controlled by modules on Bus D, such as power windows, seat memory, or climate control
The engine may start and run normally, or it may crank without starting if the affected bus carries critical powertrain data
Often no symptoms besides the warning light, especially if the lost module is not essential for basic operation

Common causes, most likely first

Damaged or corroded wiring on the Bus D circuit, including chafed insulation, broken wires, or poor connector pins
A failed module that is supposed to communicate on Bus D, causing the bus to go silent or drag down the network
Water intrusion or contamination in a connector or module housing on the Bus D segment
Loose or corroded battery terminals or ground connections that disrupt module power and communication
Aftermarket accessories improperly tapped into the bus wiring, introducing noise or a short
A faulty gateway module or central communication interface that routes messages between buses
Software or configuration mismatch in a module that prevents it from joining Bus D correctly

How to diagnose and fix it

Connect a scan tool and record all stored codes in every module, then clear codes and verify whether U0055 returns immediately or only after a drive cycle
Inspect the battery, terminals, and main grounds for tightness and corrosion, and load-test the battery to rule out low voltage as a communication fault trigger
Locate the Bus D wiring and connectors using the vehicle's service information, then perform a visual inspection for chafing, water intrusion, and loose pins
Measure resistance and voltage on the Bus D data lines with a digital multimeter to check for opens, shorts to ground, or shorts to power
Disconnect modules one at a time from the Bus D segment and recheck communication to isolate a module that is dragging the bus down
Repair or replace damaged wiring, connectors, or the faulty module identified in the previous steps, then clear codes and confirm communication is restored
If the fault persists, check for technical service bulletins (TSBs) or software updates for the gateway or affected modules before replacing expensive parts

Before you replace the gateway module

A weak or failing battery is a common cause of U0055 because modules may drop offline when voltage sags during cranking, so always load-test the battery before condemning any module.
Aftermarket alarms, remote starters, or phone chargers plugged into the data-link connector can introduce noise on Bus D and set this code, so remove non-factory accessories during diagnosis.
The code does not always mean a module has failed; a single chafed wire in a door hinge or trunk loom can short the bus intermittently and set U0055 only on bumpy roads.
Some vehicles use a terminating resistor at each end of the bus, and a missing or corroded resistor can cause communication loss that mimics a failed module.
U0055 can be stored alongside codes in other modules that are simply reporting the loss of Bus D, so focus diagnosis on the bus itself rather than replacing every module that sets a code.

Can I keep driving with U0055?

If the vehicle starts, runs, and drives normally, you can usually drive it to a repair shop, but avoid long trips and be prepared for warning lights or accessory failures. If the engine cranks without starting or multiple safety systems are disabled, stop driving and have the vehicle towed to prevent unsafe operation.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.