U0002moderate severityNetwork
High Speed CAN Communication Bus Performance
on 2019 Mazda Mazda3 2.5L I4 · FWD
What this code means
The high-speed CAN bus is operational but data integrity or timing is degraded. Bus communication is intermittent or corrupted.
Symptoms
- Intermittent warning lights
- Sporadic communication errors
- Occasional system dropouts
- Scan tool intermittent connection
Common causes
- Partially damaged CAN wiring
- Corroded CAN bus connector
- Weak termination resistor
- Electromagnetic interference
- Module with degraded CAN transceiver
Diagnostic steps
- Scope CAN H and CAN L for signal quality
- Check CAN bus termination resistance
- Inspect wiring for partial damage
- Check for aftermarket devices on bus
- Isolate modules to find degraded transceiver
Repair notes
Intermittent CAN issues often caused by corroded connectors or partially damaged wiring. Check all CAN bus splices.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
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
U0028
Vehicle Communication Bus A Performance