U0004high severityNetwork
High Speed CAN Communication Bus (+) Low
on 2014 Lincoln MKX 3.7L V6 · AWD
What this code means
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.
Other Network codes on this vehicle
U0001
High Speed CAN Communication Bus
U0001
High Speed CAN Communication Bus
U0002
High Speed CAN Communication Bus Performance
U0002
High Speed CAN Communication Bus Performance
U0003
High Speed CAN Communication Bus (+) Open
U0003
High Speed CAN Communication Bus (+) Open
U0005
High Speed CAN Communication Bus (+) High
U0005
High Speed CAN Communication Bus (+) High
U0006
High Speed CAN Communication Bus (-) Open
U0006
High Speed CAN Communication Bus (-) Open