Error code
OBD2 U0021
OBD2U0021
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.
What it means
Low Speed CAN Communication Bus (Open).
Severity
severeDriving may be possible but could lead to further damage and reduced vehicle functionality.
Summary
U0021 indicates an open circuit in the low-speed CAN data bus (+) line, which is part of the Controller Area Network (CAN) system.
Common Causes
- Loose or damaged connector
- Faulty wiring harness
Fixes
FAQ
What does U0021 mean?
U0021 indicates an open circuit in the low-speed CAN data bus (+) line, which is part of the Controller Area Network (CAN) system.
How do I fix U0021?
Fixing U0021 typically involves checking for loose or damaged connectors and faulty wiring harnesses. Professional diagnosis may be required to identify and repair the issue.
Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
More OBD2 codes
- U0001High Speed CAN Communication Bus
- U0002High Speed CAN Communication Bus (Performance)
- U0003High Speed CAN Communication Bus (Open)
- U0004High Speed CAN Communication Bus (Low)
- 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 to Bus)
- U0010Medium Speed CAN Communication Bus
- U0011Medium Speed CAN Communication Bus (Performance)
- U0012Medium Speed CAN Communication Bus (Open)