U1001moderate severityNetwork
CAN Communication Bus Fault - No Message
on 2021 Mazda Mazda3 2.5L I4 · FWD
What this code means
A required CAN bus message is not being received. A specific module is not broadcasting its data.
Symptoms
- Specific system not responding
- Warning light for affected system
- Feature disabled
- Other modules compensating
Common causes
- Module not powered
- Module failure
- CAN bus wiring open for that module
- Module in sleep mode stuck
- Fuse blown for module
Diagnostic steps
- Identify which module message is missing
- Check fuse for that module
- Test power and ground
- Check CAN wiring to specific module
- Try to wake module with scan tool
Repair notes
Identify the non-broadcasting module and check its power supply and CAN bus connection.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
U0002
High Speed CAN Communication Bus Performance
U0003
High Speed CAN Communication Bus (+) Open
U0004
High Speed CAN Communication Bus (+) Low
U0005
High Speed CAN Communication Bus (+) High
U0006
High Speed CAN Communication Bus (-) Open
U0007
High Speed CAN Communication Bus (-) Low
U0008
High Speed CAN Communication Bus (-) High
U0009
High Speed CAN Communication Bus Shorted Together
U0010
Medium Speed CAN Communication Bus