U0022 DTC: Low Speed CAN Communication Bus (-) Open

What Does U0022 Mean?

Diagnostic Trouble Code (DTC) U0022 indicates that the vehicle has detected an open circuit in the Low-Speed CAN Bus Low (CAN-) communication line. When the CAN Low wire is disconnected or broken, control modules cannot exchange information correctly, resulting in communication faults and abnormal operation of multiple electronic systems.

Symptoms

• Check Engine Light illuminated
• ABS, Airbag, or Traction Control warning lights
• Body control system malfunctions
• Power windows, mirrors, or door locks stop working
• HVAC system operates incorrectly
• Communication errors with a scan tool
• Intermittent electrical faults

Common Causes

• Open CAN Low (CAN-) wire
• Damaged wiring harness
• Loose connector or terminal
• Corroded electrical pins
• Water intrusion inside connectors
• Faulty BCM or another control module
• Incorrect aftermarket wiring installation

Typical Diagnostic Flow

Battery

│

▼

Scan Tool

│

▼

Inspect Low-Speed CAN Low

CAN High (+) ────────────── CAN Low (-) ──────────────X

Open Circuit Detected

▼

Repair Wiring or Replace Faulty Module

How to Diagnose U0022

• Read all communication DTCs using a professional scan tool.
• Inspect the CAN Low wire for cuts or broken sections.
• Check connectors for corrosion, loose terminals, or moisture.
• Measure CAN bus resistance with the ignition OFF.
• Verify CAN High and CAN Low voltages using a digital multimeter.
• Disconnect control modules individually if needed to isolate the fault.

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 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
• U0023
• U0100
• U0140
• U0155

Frequently Asked Questions

Can I continue driving with U0022?

The vehicle may continue to operate, but electronic systems can become unreliable due to communication failures. Repair is recommended as soon as possible.

What is the most common cause of U0022?

The most common causes are an open CAN Low wire, damaged connectors, corrosion, or an internally failed control module.

Will clearing the code permanently fix U0022?

No. The DTC will return until the CAN Low circuit is repaired and proper network communication is restored.