U1000

Possible causes
- Controller Area Network (CAN) communication harness is open or shorted
- Faulty Engine Control Module (ECM)
- Poor harness ground connection.

Tech notes
2002 Nissan Sentra


The service bulletin suggest cleaning engine and body harness ground connection to repair problem.


When is the code detected?
When ECM is not transmitting or receiving CAN communication signal of OBD (emission related diagnosis) for 2 seconds or more.

Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)

U1000 2002 Nissan Sentra Description

Controller Area Network (CAN) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.

Each control unit transmits/receives data but selectively reads required data only.