U0201 — Communication with door control module C — communication lost

U0201 concerns communication with door control module C. Expected communication with the named network participant is no longer being received. C identifies the named door module. The generic definition does not assign that module to a universal physical door location.

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: U0201-00, U020100, UO201 (some scan tools add the fault-type byte, e.g. -00).