U0093: Vehicle Communication Bus H Performance

What it means

A fault is detected on vehicle communication bus H. The code alone does not identify the cause or the functions affected.

At a glance

• Usually lights the warning light of the system that lost communication

How it works

Bus H is a vehicle communication network used by the modules assigned to it. U0093 indicates a performance problem on bus H, meaning communication quality or message delivery is not meeting the network's expected behavior; the code alone does not identify the failed part.

Common causes

Most likely first.

1. Damaged, loose, or corroded bus H wiring or connectors
2. A control module disrupting bus communication
3. Bus termination or gateway fault

Symptoms

• Communication faults in modules using bus H
• Warning lights or messages
• Functions relying on bus H may be unavailable

How to diagnose it

1. Scan all modules for bus H codes and note which modules have communication faults or fail to respond.
2. Review freeze-frame or event data and live network status to see whether bus H errors are continuous or intermittent and which modules are affected together.
3. Inspect bus H wiring, connectors, splices, and grounds for damage, looseness, corrosion, or evidence of an earlier repair.
4. Test bus H wiring and termination according to the manufacturer's procedure, checking the affected network sections for poor continuity or signal quality.
5. If wiring and termination pass, isolate bus H modules and check the gateway using the manufacturer's procedure to identify a unit disrupting communication.

Common fixes

• Clean and secure a loose or corroded bus H connector.
• Repair damaged bus H wiring, splices, or grounds found during inspection.
• Correct a bus H termination fault confirmed by testing.
• Repair or replace a module or gateway shown to be disrupting bus H communication.

Can I keep driving?

Functions that rely on bus H may become unavailable, and warning messages can appear. Drive only if the affected functions are nonessential and all safety-related systems work normally.