U0205moderate severityNetwork
Lost Communication with Horn Control Module
on 2003 Mazda B2300 2.3L I4 · FWD
What this code means
Cannot communicate with the horn control module on vehicles with electronic horn management.
Symptoms
- Horn not sounding
- Horn intermittent
- Panic alarm no horn output
- Theft alarm no horn
Common causes
- Horn relay module failure
- CAN bus wiring
- Module power loss
- Fuse blown
- Horn assembly failure
Diagnostic steps
- Check horn fuse
- Test horn relay
- Check CAN wiring to horn module
- Test horn assembly directly
- Inspect steering wheel horn switch
Repair notes
Check fuse and horn relay first. Test horn directly with jumper wire to confirm horn works.
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