U0025 — Low-speed CAN negative-line electrical level — low electrical level

U0025 concerns low-speed CAN negative-line electrical level. The monitor reports an electrical level below its expected range. Low-speed describes the CAN network type; low describes the monitored line level. The definition supplies no universal test voltage.

Affected system: Vehicle network communication

Symptoms

• System warning may illuminate
• Affected feature may be unavailable
• Symptoms depend on the vehicle

Possible causes

• Module power or ground loss, connector or network wiring fault, or a module that stopped communicating
• Module power, ground, or connector fault
• Vehicle-specific mechanical or control issue

What to check

• Record all available module faults
• Scan all accessible modules and record which modules report the communication fault. Check battery voltage, module power and ground, connectors, and network wiring using the vehicle topology.
• Compare results with vehicle-specific service information
• Verify the repair
• Scan all accessible modules and record which modules report the communication fault. Check battery voltage, module power and ground, connectors, and network wiring using the vehicle topology.
• Repair the verified cause and rescan all affected modules

Also written as: U0025-00, U002500, UO025 (some scan tools add the fault-type byte, e.g. -00).