U0001high severityNetwork
High Speed CAN Communication Bus
on 2005 Mazda Mazda3 2.0L I4 · FWD
What this code means
General malfunction on the high-speed CAN bus network.
Symptoms
- Multiple warning lights
- Communication errors
- Some systems inoperative
- Scan tool communication issues
Common causes
- CAN bus wiring damage
- Shorted CAN H or CAN L wire
- Missing termination resistor
- Module failure pulling down bus
- Aftermarket device interference
Diagnostic steps
- Check for aftermarket devices on OBD port
- Measure CAN bus resistance (should be ~60 ohms)
- Scope CAN H and CAN L signals
- Check for damaged wiring
- Isolate modules one at a time
Repair notes
CAN bus issues can be complex. Check wiring first. Remove aftermarket devices.
Other Network codes on this vehicle
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
U0028
Vehicle Communication Bus A Performance