U0304moderate severityNetwork
Software Incompatibility with Cruise Control Module
on 2004 Audi A8 4.2L V8 · AWD
What this code means
Software incompatibility with the cruise control system causing data errors.
Symptoms
- Cruise control erratic
- Adaptive cruise not engaging
- Speed set point drifting
- Cruise control disabling unexpectedly
Common causes
- Cruise module software outdated
- Software conflict after update
- Module version mismatch
Diagnostic steps
- Check cruise control module software version
- Update module software
- Check for known software conflicts
- Verify module compatibility
Repair notes
Update cruise control module software to version compatible with other vehicle modules.
🔌 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
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