U0029moderate severityNetwork
Vehicle Communication Bus B Performance
on 2003 Audi A8 4.2L V8 · AWD
What this code means
CAN bus B performance is degraded with intermittent communication issues.
Symptoms
- Secondary systems intermittent
- Body control functions erratic
- Climate control glitches
Common causes
- Wiring degradation on bus B
- Module fault on bus B
- Poor splice connections
- Aftermarket device loading bus
Diagnostic steps
- Scope bus B signals
- Check bus B termination
- Inspect bus B wiring
- Isolate modules on bus B
Repair notes
Diagnose bus B wiring and termination. Check for aftermarket device interference.
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Bluetooth code reader (~$25)
Veepeak OBDCheck BLE →
Pairs with your phone — reads and clears codes, live data.
Serious DIY (~$100)
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
Shop-grade tablet (~$300+)
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
As an Amazon Associate, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Other Network codes on this vehicle
00003
Control Module - Defective
01304
Radio - No Communication
01312
Powertrain Data Bus - Defective
01314
Engine Control Module (ECM) - no communications
01315
Transmission Control Module (TCM) - No Communication
01316
ABS Control Module - No Communication
01317
Instrument Cluster Control Module (J285) - No Communication
01318
Immobilizer Control Module - No Communication
01321
Airbag Control Module - No Communication
U0001
High Speed CAN Communication Bus