U01BC — Communication with charge-air cooler coolant pump B — communication lost

U01BC concerns communication with charge-air cooler coolant pump B. Expected communication with the named network participant is no longer being received. The definition names pump B in the charge-air cooler circuit, rather than automatically identifying the main engine coolant pump.

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: U01BC-00, U01BC00, UO1BC (some scan tools add the fault-type byte, e.g. -00).