U0073 - CONTROL MODULE COMMUNICATION BUS A OFF

The DTC U0073 OBDII code refers to the communication circuit that exists between the different control modules of the vehicle. This circuit is called Control Area Network (CAN).

The vehicle’s controller modules can communicate and exchange information with each other because of the CAN bus. When trying to diagnose this code, maybe an automotive scanner may not be able to communicate with the vehicle depending on the affected circuit. The “A” designation may refer to the high-speed CAN bus or low-speed CAN bus, depending on the manufacturer.

• Check Engine light illumination.
• A lack of power.
• Lower fuel efficiency.
• The instrument cluster indicators light up unexpectedly all at the same time.
• The motor may not start.

Reasons to set the U0073 OBD2 trouble code:

• The CAN bus A circuit may be open or shorted.
• Short to ground on CAN bus circuit A.
• A control module may be defective.

To resolve the faults associated with diagnostic code U0073 OBDII, take into account the following steps:

• Before starting this diagnosis, make sure that there are no other codes set. If so, repair those codes first. Also, refer to the Technical Service Bulletins available for your vehicle.
• Use a DVOM and test the CAN bus communication pins to verify that they have the resistance indicated by the manufacturer in the user manual. Repair as necessary.
• Check cables or connectors for damage because it might cause resistance above the programmed range. Repair or replace as applicable.