The U0242 code indicates that the vehicle's main control system has lost communication with Headlamp Control Module B. This typically occurs when the network bus cannot transmit or receive data from the module responsible for managing specific headlamp functions.
Chafed, broken, or shorted communication wires (CAN or LIN bus) between the main controller and the module.
Moisture intrusion or corrosion in the electrical connector pins, preventing a stable data connection.
A blown fuse or a corroded ground connection that prevents the module from powering on.
Internal electronic failure of Headlamp Control Module B, rendering it unable to communicate.
A fault in the central gateway module that routes communication between different vehicle networks.
A failure in the main engine or body control module's communication circuit.
No, this is a communication code. While the lights may not work, the cause is a failure in the electronic data exchange, not necessarily the bulbs themselves.
Yes. If the module does not have power, it cannot send signals onto the network, which the computer interprets as a loss of communication.
No. It is very rare for the PCM to be the cause of a U0242 code. The issue is almost always found in the wiring, the power supply, or the headlamp module itself.