U0024 DTC: Low Speed CAN Communication Bus (-) Shorted to Bus (+)

What Does U0024 Mean?

Diagnostic Trouble Code (DTC) U0024 indicates that the Low-Speed CAN Bus Low (CAN-) communication wire is shorted to the CAN High (CAN+) wire. This fault disrupts communication between electronic control modules, causing multiple vehicle systems to lose data exchange or stop communicating entirely.

Symptoms

• Check Engine Light illuminated
• ABS, Airbag, or Stability Control warning lights
• Body control functions stop operating
• Power windows, mirrors, or door locks malfunction
• HVAC system may become inoperative
• Communication errors with a diagnostic scan tool
• Multiple network-related DTCs stored

Common Causes

• CAN Low wire shorted to CAN High wire
• Damaged or crushed wiring harness
• Melted wire insulation
• Water intrusion inside CAN connectors
• Corroded connector terminals
• Faulty Body Control Module (BCM)
• Failed control module internally shorting the network
• Improper aftermarket electrical modifications

Typical Diagnostic Flow

Battery

│

▼

Professional Scan Tool

│

▼

Inspect Low-Speed CAN Wiring

CAN Low (-)
──────────────

✖

CAN High (+)
──────────────

Short Circuit Between CAN- and CAN+

▼

Repair Wiring or Replace Faulty Module

How to Diagnose U0024

• Scan every control module for communication DTCs.
• Inspect the CAN wiring harness for damage or melted insulation.
• Disconnect modules individually to locate the short.
• Inspect connectors for corrosion or moisture.
• Measure CAN bus resistance with the ignition OFF.
• Verify CAN High and CAN Low voltages using a digital multimeter.

Typical CAN Bus Values

• CAN High: approximately 2.5–3.5 V
• CAN Low: approximately 2.5–1.5 V
• Network resistance: approximately 60 Ω (Ignition OFF)
• Actual specifications vary by vehicle manufacturer.

Estimated Repair Cost

• CAN wiring repair: $80–300
• Connector replacement: $30–150
• Professional CAN diagnosis: $100–250
• Control module replacement: $250–1,000+

Related DTCs

• U0021
• U0022
• U0023
• U0100
• U0140

Frequently Asked Questions

Can I drive with U0024?

The vehicle may still operate, but important electronic systems can become unreliable due to communication failures. The fault should be repaired as soon as possible.

What is the most common cause of U0024?

The most common causes are damaged CAN wiring, melted insulation allowing CAN High and CAN Low wires to touch, water intrusion, or a faulty control module.

Will clearing the DTC permanently fix U0024?

No. The code will continue to return until the short circuit in the CAN communication network has been repaired.