Lost Communication - General Bus Timeout
2014-2014 Audi A6 3.0L Supercharged V6
The 2014 Audi A6 is equipped with a 3.0L V6 engine. Below you'll find detailed u1040 diagnostic code information including labor time estimates, cost ranges, and technician notes specific to this engine configuration.
Description
General timeout on the communication bus. Multiple modules are not responding within expected time.
Symptoms
- Multiple systems intermittently offline
- General communication degradation
- Multiple timeout DTCs stored
- Scan tool slow response
Common Causes
- CAN bus overloaded
- Poor bus termination
- Multiple modules with slow response
- Bus wiring degradation
- Power supply instability affecting modules
Diagnostic Steps
- Check bus termination resistance
- Monitor bus load with scope
- Check power supply voltage to modules
- Test for intermittent connections
- Remove aftermarket CAN devices
Repair Notes
Check bus termination and overall bus health. Overloaded buses cause timeouts.
Related Codes
Other Network Codes
- U0001High Speed CAN Communication Bus
- U0001High Speed CAN Communication Bus
- U0002High Speed CAN Communication Bus Performance
- U0002High Speed CAN Communication Bus Performance
- U0003High Speed CAN Communication Bus (+) Open
- U0003High Speed CAN Communication Bus (+) Open
- U0004High Speed CAN Communication Bus (+) Low
- U0004High Speed CAN Communication Bus (+) Low
- U0005High Speed CAN Communication Bus (+) High
- U0005High Speed CAN Communication Bus (+) High
U1040 on Other Vehicles
Common Questions
What does code U1040 mean on a 2014-2014 Audi A6?
U1040 stands for "Lost Communication - General Bus Timeout". General timeout on the communication bus. Multiple modules are not responding within expected time.
What are the symptoms of U1040 on a Audi A6?
Common symptoms of U1040 include: Multiple systems intermittently offline, General communication degradation, Multiple timeout DTCs stored, Scan tool slow response.
What causes U1040 on a 2014-2014 Audi A6?
Common causes of U1040 include: CAN bus overloaded, Poor bus termination, Multiple modules with slow response, Bus wiring degradation, Power supply instability affecting modules.
Last updated: March 2026