U0072: Vehicle Communication Bus E (-) Shorted to Bus E (+)

What it means

A short between the positive and negative conductors of vehicle communication bus E is detected.

At a glance

• Usually lights the warning light of the system that lost communication
• The engine or gearbox may go into limp mode

How it works

Bus E uses positive and negative conductors to carry messages among connected modules. U0072 means the negative conductor is shorted to the positive conductor, collapsing the separation between the two signal lines and preventing reliable communication.

Common causes

Most likely first.

1. Persistent short on CAN-L wire
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Scan all modules and save freeze-frame data and communication codes to identify which network devices lost contact when the fault occurred.
2. Inspect both Bus E conductors together along the harness, especially at bends, clips, splices, and connectors, for crushed insulation or wires touching.
3. With power isolated as specified by the manufacturer, test for continuity or a short between the Bus E negative and positive conductors in the affected sections.
4. Check bus termination resistance at the specified points and compare the measurement with the manufacturer's specification.
5. If no harness short is found, isolate Bus E modules and check gateway routing using the manufacturer's diagnostic procedure.

Common fixes

• Separate and repair Bus E negative and positive wires that have contacted each other.
• Replace damaged insulation or repair the connector or splice where the lines are bridged.
• Repair an out-of-spec termination connection or component identified by testing.
• Repair or replace a faulty gateway or module if isolation testing identifies it.

Can I keep driving?

Avoid driving when connected systems are unavailable or the vehicle enters limp mode, and do not rely on affected safety functions. A short between Bus E conductors can cause broad or intermittent communication loss.