Code U0115 indicates that a module on the vehicle's communication network has lost contact with the Engine Control Module (ECM) or Powertrain Control Module (PCM). This is a network communication error rather than a direct sensor failure, meaning data is not flowing between the engine computer and other onboard systems.
Frayed, broken, or shorted CAN bus wiring between the ECM and other network modules.
Moisture or corrosion in the ECM pins or connector housings preventing a secure electrical connection.
Blown fuses, faulty relays, or loose ground wires that prevent the ECM from powering on.
A different module on the same communication bus failing and flooding the network with noise.
The engine computer has suffered an internal hardware failure and is no longer broadcasting data.
Not necessarily. While the PCM is a possible cause, it is far more common for the issue to be a broken wire, a blown fuse, or a corroded connector.
Yes, low system voltage can cause modules to shut down or fail to communicate, triggering network loss codes.
Many vehicle systems (ABS, Airbags, Transmission) rely on data from the ECM to function; if they stop receiving that data, they will trigger their own fault lights.