High Speed CAN Communication Bus (+) Low
2007-2014 Land Rover LR2 3.2L I6
Description
The CAN High wire voltage is lower than expected, indicating a short to ground or excessive load on the bus.
Symptoms
- Communication failures
- Multiple DTCs from various modules
- Intermittent system operation
Common Causes
- CAN H wire shorted to ground
- Module pulling CAN H low
- Damaged wiring insulation
- Water intrusion in connector
Diagnostic Steps
- Measure CAN H voltage
- Disconnect modules one at a time to find short source
- Inspect wiring for chafing against ground
- Check connectors for moisture
Repair Notes
Find and repair the short to ground on the CAN H wire. Inspect for damaged insulation.
Related Codes
Other Network Codes
- U0001High Speed CAN Communication Bus
- U0002High Speed CAN Communication Bus Performance
- U0003High Speed CAN Communication Bus (+) Open
- U0005High Speed CAN Communication Bus (+) High
- U0006High Speed CAN Communication Bus (-) Open
- U0007High Speed CAN Communication Bus (-) Low
- U0008High Speed CAN Communication Bus (-) High
- U0009High Speed CAN Communication Bus Shorted Together
- U0010Medium Speed CAN Communication Bus
- U0028Vehicle Communication Bus A Performance
U0004 on Other Vehicles
Land Rover Defender 110
2020-2024 3.0L I6 Mild Hybrid
Land Rover Defender 90
2020-2024 3.0L I6 Mild Hybrid
Land Rover Defender V8
2022-2024 5.0L V8 Supercharged
Land Rover Discovery
1994-2004 4.0L V8
Land Rover Discovery
2017-2024 3.0L V6 Supercharged
Land Rover Discovery Sport
2015-2024 2.0L I4 Turbo
Land Rover Freelander
1997-2006 2.5L V6
Land Rover LR3
2005-2009 4.4L V8
Common Questions
What does code U0004 mean on a 2007-2014 Land Rover LR2?
U0004 stands for "High Speed CAN Communication Bus (+) Low". The CAN High wire voltage is lower than expected, indicating a short to ground or excessive load on the bus.
What are the symptoms of U0004 on a Land Rover LR2?
Common symptoms of U0004 include: Communication failures, Multiple DTCs from various modules, Intermittent system operation.
What causes U0004 on a 2007-2014 Land Rover LR2?
Common causes of U0004 include: CAN H wire shorted to ground, Module pulling CAN H low, Damaged wiring insulation, Water intrusion in connector.