U0012moderate severityNetwork
Control Module Communication Bus A Shorted To Bus A High
on 2013 Ram 2500 6.7L I6 Cummins Diesel · 4WD
What this code means
The low side of communication bus A is shorted to the high side, corrupting data traffic. This causes loss of communication between modules.
Symptoms
- Communication error codes
- Warning lights illuminated
- Loss of module function
Common causes
- Wiring short between bus A high and low
- Chafed harness insulation
- Faulty control module
- Damaged connector
Diagnostic steps
- Scan for stored U-codes
- Check resistance between bus A wires
- Inspect harness for pinched wires
- Test individual modules
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, 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